Adaptable recharging and lighting station and methods of using the same

ABSTRACT

The present invention includes self-contained, rechargeable power systems for areas having unreliable electrical grids or no electrical grid at all, and methods related thereto. The system may include one or more solar panels of various sizes to provide an off-grid power generation source, battery receivers for receiving batteries of various chemistries, and a control circuitry that is operable to detect the voltage and/or current output of the batteries that are installed in the system to determine their specific battery chemistry and then adjust the charge algorithm of the batteries to optimize both the charge capacity and the cycle life of the batteries. The control circuitry may also be operable to switch configurations of the solar panels and/or the batteries to optimize performance of the system. The system may be operable to power one or more light emitters and/or external electronic devices connected through the system by a charge port.

FIELD OF THE INVENTION

The present invention relates to a charging and lighting station, andmore particularly to a solar power/recharging station for poweringlights and external electronic devices, and recharging batteries andrechargeable devices, and methods of using and operating the same.

BACKGROUND OF THE INVENTION

Devices that utilize rechargeable batteries and solar panels forcharging the batteries are useful in underdeveloped and developingcountries and in remote areas where there is no reliable electric powergrid system available. Alternative power sources for lighting, powering,and recharging devices are needed more than ever because of the modernproliferation and reliance upon electronic devices for communication.

Such systems typically have set, inflexible designs that include only aspecific solar panel or set of solar panels and a specifically designedbattery or a specific type of battery. The designers of such systemsoften constrain the design, making it easier to implement. Thus, thepurchaser or user of such systems typically has no options forexpanding, changing, or adjusting such systems. Such systems typicallyhave a specific, custom solar panel. This allows the designer to dictatethe exact voltage and current input to the circuit. However, thiseliminates choice and upgradeability for the consumer. For instance, tocontrol the cost of the product a designer may choose to provide a lowpower solar panel with the product, which works well in regions of theworld with high incidence of solar radiation. If that product is soldwhere cloud cover is common or there are other causes of low solarradiation, the custom solar panel will not produce enough energy toproperly power the unit. And because the solar panel is custom to thatspecific product, adding another solar panel to the product or changingthe panel to a higher power solar panel to increase the power input tothe circuit is often not an option for the consumer.

Such systems or products are also often designed around one batterytype, requiring the purchaser to replace the batteries with the sametype of batteries as needed. Some products will accept third partyprimary (non-rechargeable) or secondary (rechargeable) batteries ofstandard sizes that can be purchased from various sources. However, theuser of the system or product may be confused because of there may beseveral different battery chemistries available within the same batterypackage size (e.g., AA, AAA, D, etc.). Consequently, systems limited toa single battery chemistry create a risk that the user will installbatteries having chemistries that are incompatible with the system,which may result in system malfunction. Malfunctions can occur byinstalling batteries having a voltage that is too high or too low forthe design of the system. Malfunctions can also occur if the product isdesigned to recharge secondary batteries, but primary batteries areimproperly installed. In addition, the wrong type of secondary batteries(with the wrong chemistry) can damage the unit when they are installedbecause the system will apply its standard charging algorithm, which maybe incompatible with the battery chemistry. A purchaser may even installseveral different types of batteries within the same unit, compoundingthese same issues. Thus, when the designer constrains the design to onespecific battery type, the risk of product failure due to installationof the wrong battery type is then transferred to the purchaser, who islikely unaware of the risk.

Other manufacturers may eliminate the risk that the user will installthe wrong batteries by designing a custom battery pack that is unique tothe product. The custom battery pack may or may not be replaceable. Ifthe battery pack is not replaceable, the product is unfortunatelydiscarded when the batteries no longer function, which results in wasteof materials and costs. In other cases, the product may be designed toallow for the replacement of the custom battery pack when the batterypack no longer functions. Because custom battery packs are arranged andinstalled in the product in specific configurations and the product isnot designed to charge one battery at a time, but rather the entirecustom battery pack, the batteries are charged in an unbalanced andinefficient manner that results in a relatively short battery life forthe custom battery packs and forces the consumer to purchase a newcustom battery pack after relatively few charge-discharge cycles(referred to as “cycle life”). Typically, the custom battery packs areonly available through the manufacturer who sells the custom replacementbatteries to the consumer, or through 3^(rd) party vendors sellingknock-offs that are often inferior and/or unreliable.

Consumers may not understand that all batteries (primary and secondary,and custom battery packs) fail over time. Because it is often notobvious to the consumer how to replace the batteries, the product isjust set aside or thrown away, which may result in the consumer faultingthe designer with creating a “cheap” product. For the consumer thatunderstands that all batteries will eventually fail, there are otherdisadvantages to this design method. The need for a manufacturer orauthorized agent to replace the batteries can put an undue hardship onthe consumer, especially those in remote areas which have the greatestneed for battery-powered products. Also, “custom” battery packseliminate or reduce the likelihood of competition for the supply ofreplacement batteries for the manufacturer's product, likely resultingin higher costs for the replacement battery and the product.

The battery design choices made by the product manufacturers are drivenby the power requirements of the device, the battery chemistries thatare currently available, the risk of damage to the particular productthat would result from installation of the wrong battery type, and otherfactors. Once the manufacturer determines the appropriate battery type,required current, and required voltage, the designer then devises a wayfor the batteries to be installed in the product. The batteries will beconfigured in series, or parallel, or perhaps a combination of both. Dueto the constrained design, the batteries will always be installed in thesame arrangement so that the proper voltage and current are achieved forthe product. As already noted, the designer will often choose to providea custom battery pack with the configuration determined at the factory,and so that they cannot be changed by the consumer.

The battery configuration chosen by the manufacturer may be optimizedbased on its discharge and charging characteristics. Since the battery'slongevity depends on the output current, one battery configuration maybe best for charging life of the battery pack. But based on the inputpower being used to charge the batteries, a different configuration maybe best for charging. Since the user cannot be relied upon to change thephysical configuration of the batteries based on the batteries beingused to supply power versus when the batteries are being charged, thedesigner is forced to compromise one for the other when setting a singlebattery configuration.

There are many different battery chemistries available to devicemanufacturers, For example, the AA and the size-compatible 14500 batterypackages may be made to utilize primary, such as zinc-carbon (dry cell),zinc-chloride, alkaline, or lithium chemistry; or a secondary chemistry,such as NiCd, nickle-metal hydride (NiMH), NiZn, LiFePo₄, or lithium ionchemistry. The different chemistries all have different strengths andweaknesses, and all have different monetary prices to the purchaser. Ofthe secondary type, different chemistries yield different amounts ofrecharge cycles (the literature reports anywhere from 200 rechargecycles to 2000 recharge cycles, depending on the chemistry). Also,different chemistries yield different output voltages, ranging from 1.2Vnom to 3.7V nom. Different chemistries may also be best used withdifferent discharge rates (the literature reports recommended dischargerates anywhere from 80 mA to 500 mA). In addition, as a battery is usedto provide current, its voltage drops overtime in a way that is uniquelycharacteristic to its chemistry. Because of the variations in thecharacteristics of the different chemistries, it is standard practicefor designers to first choose a specific battery chemistry in order tosimplify the product design. Once the designer has determined thebattery chemistry, the number of battery cells and their configuration(series, which adds voltage, or parallel, which adds current) must beselected, taking into account the overall range of voltage through theentire discharge curve of the particular battery type. These factorsmust be balanced with expected life of the battery and cost of thebattery. These design choices result in a specific and constraineddesign. Often, the chosen design does not satisfy the preferences of allconsumers, and thus may alienate a certain portion of the market.

There are particular markets in which the availability of power sources,including batteries, is limited and presents a significant economicburden to the local population. Solar power has been promoted as apotential power source for these underserved regions, but power storagefor use in dark and night conditions is necessary to provide aconsistent power source for such regions. Systems that are limited tospecific battery chemistries can present a problem for the populationsin these remote areas because batteries may be relatively scarce and thespecific battery type required by the system may not be available. Thus,there is a need for systems that are able to accommodate multiple powerand battery options.

SUMMARY OF THE INVENTION

The present invention includes devices that provide power for lightingand charging batteries and/or other electronic devices that canaccommodate and utilize multiple power sources. More specifically, thepresent invention relates to a customizable system that may include oneor more lamps and one or more charging ports for external electronicdevices that utilize solar and/or battery power, where the systemincludes control circuitry that is operable to do one or more of thefollowing: (1) identify the type of battery installed in the system, (2)switch between parallel and series configurations of batteries duringcharging based on the power available from a power source (e.g., solarpanels), (3) switch between parallel and series configurations ofbatteries during discharging based on the chemistry of the batteries andthe load on the system, (4) switch between power sources (e.g., frombatteries to solar panels) for powering lights and/or charging anexternal electronic device, (5) switch between charging and dischargingof one or more batteries installed therein based on the output of solarpanels in the system and a load connected to the system, and (6) switchbetween series and parallel configurations of the solar panels tooptimize voltage and current outputs for particular use (e.g., chargingbatteries and/or powering a load, such as a mobile phone), and methodsof using the same. The invention is particularly suitable for use inremote locations and underdeveloped locations where there is no powergrid system or the existing power grid system is unreliable.

Embodiments of the present invention may combine solar power, lights,batteries, one or more electronic control circuitries, andmicroprocessor firmware in a novel lighting system that gives theconsumer considerable choice and customizability in the use of theproduct while maximizing the life to the system and minimizing theoverall cost of ownership of the system. The elements of the system canbe mixed and matched depending on the user's preferences. For example,the system may include multiple lamps, one or more solar panels ofvarious sizes (3 W, 5 W, 10 W, etc.), and rechargeable batteries of aparticular size (e.g., AA/14500), but of variable chemistry (e.g., thesystem is designed such that it can accommodate multiple batterychemistries, such as NiCd, nickle-metal hydride [NiMH], NiZn, LiFePo₄,or lithium ion chemistry). The system is operable to accommodatemultiple battery chemistries because the firmware of the system isoperable to (1) test and identify the type of batteries installed in thesystem based on the voltage output of the batteries, (2) adjust theconfiguration of the batteries between series and parallel based on theoutput voltage of the batteries or the voltage and current available tocharge the batteries, and (3) apply a charging algorithm to thebatteries that is adapted and optimized to the particular chemistry ofthe installed batteries. The system may be particularly useful in thirdworld or lesser developed markets where power grids are absent orunreliable. The system provides a relatively inexpensive andself-charging light source and charging station.

The present invention avoids design constraints that manufacturers haveaccepted in the past, particularly with respect to battery requirementsand solar panel requirements. The charging and power system of thepresent invention may accept both primary (non-rechargeable) (e.g.,NiCd, nickle-metal hydride [NiMH], NiZn, LiFePo₄, lithium ion chemistry,etc.) of the installed batteries are identified by the microprocessorusing a series of tests of electrical characteristics (e.g., voltage) ofthe batteries. The microprocessor may have firmware logic enabling it toanalyze voltage readings from one or more configurations (e.g., series,parallel, and other specialized configurations) and other sensorreadings (e.g., temperature sensor readings) sensors that areconductively connected to the batteries at one or more positions and/orare in proximity to the batteries. The battery class detection methodsmay allow the microprocessor to automatically adjust the configurationof multiple batteries installed in the system between series andparallel arrangements to optimize the battery discharge for powering thelighting elements connected to the system and, in some cases, poweringone or more charging ports for external electronic devices. Embodimentsof the present invention may also optimize the recharging of theinstalled batteries, in some cases while powering a USB charge port,based on power output from one or more solar panel(s). This inventionalso allows the user to power the system by installing primary batteries(which the system will recognize and not charge) or a mixed group ofbatteries of different chemistries (e.g., a alkaline battery incombination with NiMH batteries). This capability allows the user topower the system regardless of what kind of batteries are available tothe purchaser. However, in such situations the batteries may only beused for lighting and charging electronics, and cannot be recharged.

To prevent damage to the system, the embodiments of the presentinvention may include safeguards to protect the device from theinstallation of various battery types (e.g., from a voltage surge fromthe installation of relatively high voltage batteries, such as Li ionbatteries) or mixed battery types, while still allowing operation of thelamp and charging of external electronic devices that may beelectronically connected to a charge port in the system. The electronicsand firmware are designed in a manner that allows the system to analyzethe voltage and current characteristics of the batteries in order todetermine the type of batteries (the battery chemistry) of the installedbatteries. Thus, the system may automatically discern the type ofchemistry of the batteries that are installed to determine whether thebatteries can be charged, and, if so, what specific charge algorithmshould be used for charging the installed batteries. In this manner, thesystem may optimize the usable life of the installed batteries.

Additionally, the system's capability to identify the specific batterychemistry of the installed batteries allows the system to balance chargethe specific battery type. Balance charging avoids the differentialcharging that results from charging batteries in series or parallelconfigurations. When multiple batteries are charged together, if theirinternal resistance is not precisely matched to one another, the batterywith the lowest internal resistance accepts more current than the otherbatteries and therefore will charge faster than the other batteries.Over time, the differences between the batteries' charges can becomelarge and the total charge of the group of batteries may be diminished.Balance charging, or charging one battery at a time to its fullpotential, avoids this issue. The present system is operable to balancecharge a single battery installed in a battery receiver of the system(e.g., one battery slot of a plurality of battery slots in the system).The system is operable to recognize that a single battery has beeninstalled and is operable to measure the individual voltage (or current)produced by the battery. The battery receivers may be configured intoparallel configuration during the balance charge operation, allowing thesingle battery to be charged (e.g., if the battery receivers wereconfigured in series, no complete circuit would be formed and no balancecharging would be possible).

The system may include firmware and at least one microprocessorelectronically connected and arranged such that the power generated bythe one or more solar panels of the system can be monitored andallocated to optimize the performance of the system, including poweringlighting elements in the system and charging external electronicdevices. The electronic circuitry, firmware, and microprocessor of thepresent invention may control the solar power generated by the one ormore solar panels, the power allocated to the lighting source, thecharging and discharging of the batteries (which may be of varyingchemistry), and the charging of an attached external electronic devicein a novel way to create a home lighting and charging system that givesthe consumer a flexible and consistent system that can power lamps (andother devices) and charge in various off-the-grid environments andsituations. The system also provides substantial customizability in thecomponents of the system to allow the user to adjust the system to hisneeds within the environmental, market, and economic constraints of aparticular location.

As mentioned above, embodiments of the present invention may use solarpanels as a power generation source. Certain semiconducting materialsexhibit the photovoltaic (PV) effect of converting photons from the suninto the flow of electrons for use in electrical systems. PV materialsmay be configured in such a way as to create solar panels for thegeneration of electricity from solar radiation. The current and voltagegenerated by solar panel technologies are related to each other, buttheir relationship is highly non-linear. Thus, creating an operationpoint in which concomitantly generated current and voltage provides amaximum power point of operation (Power=generated voltage*generatedcurrent at that voltage) may provide for more efficient powergeneration. For instance, solar panels that are designed to charge 12Vbatteries have a maximum power point of approximately 17V. At 17V, apanel capable of producing 10 W will produce 0.59 A (17V*0.588 Å=10 W).When the panel is not supplying any current (open circuit) the panelwill produce 21.6V, but the power output is 0.0 W due to no current.When the panel produces its maximum current of 0.68 Å, the voltage dropsto a very low value, approximately 3V, thus producing only 2 W. Thus, itis desirable for the designer to provide a means to operate the panel atits maximum power point (MPP) whenever possible. FIG. 1 provides a graphof current-voltage curves for a 12V, 10 W solar panel at severaltemperatures (25° C., 50° C., and 75° C.). The current-voltage curves ofFIG. 1 demonstrate both the MPP of solar panels at a given light level(standard test conditions: irradiance at AM 1.5, 1 kw/m²) and theflexibility for harvesting current and voltage from the solar panel. Forexample, if more current is needed, more current can be drawn at theexpense of a lower voltage. Such adjustments may be useful innon-optimal solar conditions. Under low light conditions, there may beinsufficient current provided at the MPP to run lights and/or chargeattached, external devices, and it may be advantageous to draw morecurrent and lower voltage (e.g., move from the MPP to the left side ofthe current-voltage curve).

The system may include one or more solar panels that can be used togenerate power for charging the batteries installed in the system, torun the lighting elements (e.g., LEDs) of the system and other devices(e.g., USB compatible devices), to charge a device (e.g., a mobilephone) connected to a USB port, to charge secondary batteries installedin the system, or combinations thereof. The firmware allows themicroprocessor to automatically recognize the power available fromattached solar panels and optimize the battery configuration (e.g.,parallel or series), the solar power configuration (e.g., parallel orseries), and/or the charge algorithm for optimum performance (e.g., theamperage applied to the batteries) based on the dynamically changingoutput of the solar panel (which varies depending on season of the year,weather, and environmental conditions: clouds, low-light conditions,etc.).

In some embodiments, the system may also include firmware andelectronics capable of automatically adjusting the electronicarrangement of multiple solar panels (e.g., between series and parallel)and the output voltage to optimize the voltage available for charging ofbatteries installed in the system and the power supplied to devicesconnected to the system. While it is not required that multiple solarpanels be installed in the system, the system is capable of connectingto multiple solar panels and manipulating the electronic configurationof the solar panels. The system may include a solar panel control logiccircuit operable to switch a plurality of solar panels from parallel toseries configuration and vice versa in response to a number ofconditions in the system. For example, if there is a change in lightconditions (e.g., the available sunlight is diminished due to anincrease in cloud cover), the configuration of the solar panels may bechanged from a parallel configuration to a series configuration in orderto increase the total voltage produced by the solar panels. The solarpanel control logic circuit may reverse the configuration back to aparallel arrangement if the solar conditions improve. Additionally, thesolar panel control logic circuit may change the configuration of thesolar panels from parallel to series if there are multiple simultaneousdemands on the power generated by the solar panels, such as an externaldevice (e.g., a mobile phone) plugged into a USB port of the system forcharging while installed batteries are being charged. In response to themultiple demands on the system, the solar panel control logic circuitmay configure the solar panels in a series configuration. The solarpanel control logic may change the configuration of the solar panels inresponse to signals from the control processor of the system, whichmonitors voltage demands created by various elements in the system (suchas the lighting elements, the batteries, and any connected externaldevices) through circuit connections to these elements, and analyzes thevoltage demands created by these elements and signals the solar panelcontrol logic to change the configuration of the solar panels betweenseries and parallel based on the analyzed voltage and current demands.

In addition, this product allows the consumer to choose solar panelsthat best fit their needs, based on size, price, and performance, andfor customization at the user's convenience. For example, the user maychoose a smaller solar panel initially when the system is purchasedbased on the lower cost of the solar panel, and in the future maypurchase a larger panel or an additional small panel when funds areavailable to increase the power available to the system. When changesare made to the system (e.g., one or more solar panels are added), thesystem automatically recognizes the power available from attached solarpanel(s) and optimizes the battery and/or panel configuration (series orparallel) and charge algorithm for optimum performance based on thedynamically changing output of the solar panel. Also, the system mayrecognize fluctuations in the power output of the solar panel(s) thatmay result from solar conditions (e.g., changes in sunlight due toovercast conditions), and adjust the battery and/or solar panelconfiguration and charge algorithm to balance and optimize the output ofthe system (lighting and charging of electronic devices) and thecharging of the batteries. If the solar panel(s) cannot produce enoughcurrent at its maximum power point to provide power for lighting and/orcharging an attached electronic device, the unit will adjust itsconfiguration to draw maximum current, and then automatically adjust theconfiguration again when the maximum power point can be maintained.

The system may use various kinds of lighting elements for providinglight to the user, and may include multiple light emitters of the sameor different kind. In some embodiments, the system may be limited tolight emitting diodes (LED) as a light source. A light emitting diodedraws a specific amount of current at a given voltage, where the higherthe available supply of voltage, the more current the LED draws. Theamount of light that an LED produces is a direct function of the amountof current going through it, yielding a relation to the voltage that isbeing supplied to it. When operated from battery power, the dischargecurve of the battery needs to be accounted for; the more the batterydischarges, the lower its voltage, and thus decreasing the amount ofcurrent going through the LED, and thus decreasing the amount of lightthat is produced by the LED. In addition, the life expectancy of a LEDis determined by the amount of current going through the LED. If thecurrent is below a certain threshold, the LED will last tens ofthousands of hours. If the threshold is violated, the life the LED willbe diminished. Also, LEDs have maximum current limitations, thus theamount of voltage that is supplied to them should be controlled in orderto avoid damage to the LED.

For the foregoing reasons, it is advantageous to monitor and control theamount of current and voltage supplied to an LED. Pulse width modulation(PWM) may be employed to maintain constant current through a relativelybroad range of supply voltages. The firmware may control the PWM of thepower source that powers LED lamp, where the power source may be thebatteries, the solar panel operating at its maximum power point, or fromlow wattage solar panels operating at the LED operating voltage. Forexample, when the unit is connected to one or more solar panels and thepower provided by the solar panel(s) is sufficient to power the LEDlamp, the batteries may be electrically isolated from the lamp so thatlamp is operated from solar panel and not from batteries to save thebatteries' charges. PWM can be used to maintain the average currentgoing through the LED within a closed loop feedback system by adjustingthe duty cycle of high-speed pulses of voltage. The average current overa period of many pulse cycles is calculated and maintained by theprocessor. However, the applied current is maintained below peak currentof the LED, even if that peak is for a very short duration in the PWMcycle.

The solar panel may power the lighting elements (e.g., LED) directly, orthrough a step-down (buck) converter to step down the voltage and stepup current. The solar panel may directly power the LED lamp if the solarpanel's output is within the operating voltage of the LED. However, ifthe voltage of the solar panels is beyond the limit for the LED lamp setby the controller, the controller will isolate the solar panel(s) fromthe LED lamp(s) and power will be provided to the LED lamp(s) through astep-down convertor. In some embodiments, the controller firmware candetermine the output of the solar panel and utilize MOSFET switching tochange the power supply of the LED lamp from being directly from thesolar panel(s) to being indirectly from the solar panels through thestep-down converter.

The firmware may also direct that more current and less voltage is drawnfrom the solar panel. For instance, if the solar panel cannot produceenough current at its maximum power point to power the LED, the unitwill adjust its configuration to draw maximum current, and thenautomatically adjust the configuration again when the maximum powerpoint can be maintained (e.g., there is sufficient sunlight). To do so,the firmware controls MOSFET switching to isolate the circuitry loadfrom the solar panel to allow the solar panel to recover to no-loadvoltage, and then configure circuitry to draw power from the solar panelat its maximum power point.

The electronics industry has developed standards for charging multipledevice types using universal serial bus (USB) connections withoutrequiring serial bus communications. Thus, items such as cellphones canbe charged via the same connector as is used for serial communication.USB standards require 5.0V nominal voltage for the charging operationwith varying degrees of supply current based on the specific standardand country for which the device is designed. Embodiments of the presentinvention may include one or more USB charge ports for charging externalelectronic devices. Various electronic devices are compatible with USBcharge ports via a USB cable (e.g., Standard A USB, Standard B USB, MiniA USB, Mini B USB, Micro A USB, Micro B USB, Micro AB USB, 30-pin Appledevice ports, 8-pin Apple device ports, UC-E6 plug, Nokia Pop-Port, HTCExtMicro USB port, etc.). However, some devices (e.g., older cell mobilephone technologies, computers, etc.) may not be USB compatible or theuser of the system may not have a USB adapter cable available for anexternal device. Thus, in some implementations, the system mayalternatively or additionally include power outlets and charge ports ofvarious designs (e.g., 12V vehicle charger, etc.).

Embodiments of the present invention may include a battery compartmentthat accepts multiple batteries (e.g., three, four, etc.) of a certainsize (e.g., AA/14500 batteries). The system may be able to identify andaccommodate rechargeable batteries of different chemistries (e.g., NiMHbatteries, NiCad batteries, Li-Ion or LiFePO4 batteries). The inventionmay accomplish the identification of the batteries through a machinestate coding firmware algorithm in combination with battery switchinglogic that allows the installed batteries to be switch between paralleland series configurations according to signals from the control. Thebattery switching logic may utilize P type and N type MOSFETs for itsswitching function. For example, a firmware algorithm may includemultiple voltage measurements of the batteries in series, parallel, andother arrangements (e.g., partial parallel arrangement) that allow theprocessor to determine the total voltage of the batteries in series, thevoltage of the batteries in parallel, and other voltage measurements(e.g., measuring the voltage of the batteries through a reverse bodydiode of a normally open MOSFETs to determine whether they are all ofthe same chemistry type). The battery switching logic allows for theconfiguration of the batteries for the various voltage measurementsneeded to perform the battery identification tests. The batteryswitching logic may use MOSFET switching to change the configurations ofthe batteries. The voltage measurements and firmware algorithm togetherexecute what amounts to a battery identification protocol that candetermine the particular chemistry of the installed batteries: e.g.,whether they are lithium ion batteries versus NiMH batteries (eventhough the output voltage of one lithium based battery can equal theoutput voltage of three NiMH batteries). Once the chemistry of thebatteries is identified, the firmware may apply a charging algorithm forthe installed batteries that is optimized for the charging profile ofthe particular battery chemistry.

Different batteries require different charge algorithms. For example,some battery chemistries require a preparatory or slow charge, then anaccelerated charge rate, then a very low trickle or maintenance charge.Other types require a constant current until a specific voltage isreached, and then a specific time at a constant voltage. The ability toidentify the specific chemistry of the battery allows the user tooperate the system with batteries having different chemistries, givingthe user flexibility if the availability of rechargeable batteries islimited (e.g., there is only one type of battery available). The systemmay extend or maximize the life of the chosen batteries by identifyingthe type of chemistry of the installed batteries and then using thespecific charge algorithm that optimizes the life of the battery. Thesystem also allows for balance charging of specific battery types, asmentioned above.

The firmware may also allow the processor to identify whether batterieshaving different chemistries (e.g., installing 2 NiCad and 1 LiFePO4batteries) have been installed in the battery compartment together. Todetermine when batteries of different chemistries are improperlyinstalled, the microprocessor may compare the voltage of batteries inseries compared to 3× voltage in parallel (fault if series is greater orless than 3× parallel, +/−0.3V). Another method that may be used todetermine whether batteries of mixed chemistry are simultaneouslyinstalled is to measure voltage output of the batteries in a partialparallel configuration in which both normally open (NO) and normallyclosed (NC) transistors used to switch the batteries between series andparallel configurations are in the open condition, allowing voltage topass through the transistors only through body diodes associated witheach. If the voltage difference measured using this method is less thana predetermined value (e.g., 0.4V) the system may determine that thebatteries are of mixed chemistry. The system will not charge thebatteries if it detects mixed chemistry batteries in the batterycompartment, as to not damage the batteries, but may draw power from thebatteries to allow the lighting element(s) to provide light, for as longas the batteries can supply enough power.

The firmware algorithm and MOSFET switching can also determine whenprimary batteries (non-chargeable batteries) are installed based onbattery voltage and battery temperature, allowing for operation of thelamp while preventing the charging of the primary batteries. Thetemperature of the batteries may be monitored by the microprocessor whena voltage is applied to the batteries (e.g., using a thermistor locatednear the battery compartment). If the temperature rises beyond apredetermined threshold, the microprocessor will classify the installedbatteries as primary batteries and no charging will be applied to thebatteries.

The system may also include specific circuitry to prevent excessiveinrush current while batteries are being installed, allowing forinstallation of multiple batteries in any order, and to preventexcessive inrush current while batteries are switched from parallel toseries and series to parallel.

In some embodiments, the system also automatically adjusts through theuse of firmware logic and electronics the configuration of multiplebatteries and/or attached power devices (e.g., solar panels) to optimize(1) the battery discharge for powering LED lights and, in someinstances, a USB charge port, (2) the battery charging based on thepower output available from one or more solar panel(s), and (3) solarpanel powering of the LED or the USB port when the batteries are fullycharged. The optimization may result in longer charging time for thebatteries if, e.g., the solar panel has a low output (e.g., a 3 W panelor the panel is in low-light conditions) and the charging algorithm isaccordingly changed (e.g., lower amperage is applied to charge thebatteries), or if the solar panel is simultaneously powering the LEDlight(s) and charging the batteries. For the latter situation, thesystem may use PWM operation to power the LED light(s) operation and maycompensate for a drop in power to the LED light(s) due to simultaneousbattery charging (or light conditions) and may extend the pulse width toobtain the required current to achieve the desired brightness of the LEDlamp. In some embodiments, and without limitation, the system mayrestrict the operation of the LEDs during battery charging in a reducedpower mode (e.g., the solar panel power output is reduced due to cloudcover or other conditions). There is a possibility of high voltagespikes going to the LEDs in such situations (e.g., a cloud coverpasses), and because of the very sensitive nature of LEDs toover-voltage, this protection may prolong the life of the LEDs andreduce the risk of failure of the system.

The above-described objects, advantages and features of the invention,together with the organization and manner of operation thereof, willbecome apparent from the following detailed description when taken inconjunction with the accompanying drawings, wherein like elements havelike numerals throughout the several drawings described herein. Furtherbenefits and other advantages of the present invention will becomereadily apparent from the detailed description of the preferredembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph demonstrating power (current-voltage) curves for a fora 12V, 10 W solar panel at several temperatures (25° C., 50° C., and 75°C.).

FIG. 2 is a graph demonstrating the applied current and voltage profilesof lithium ion battery during a charging operation.

FIG. 3 is an exemplary embodiment of a lighting/recharging systemaccording to the present invention.

FIG. 4 is another exemplary embodiment of a lighting/recharging systemaccording to the present invention.

FIG. 5 is a generalized system layout of the electronic components of alighting/recharging system according to an embodiment of the presentinvention.

FIG. 6 is a generalized layout of the electronic components of a batteryswitching circuit according to an embodiment of the present invention.

FIG. 7 is another exemplary embodiment of a lighting/recharging systemaccording to the present invention.

FIG. 8 is a generalized system layout of electronic components of alighting/recharging system according to another embodiment of thepresent invention.

FIG. 9 is a generalized layout of the electronic components of a batteryswitching circuit according to another embodiment of the presentinvention.

FIG. 10 is a generalized layout of the electronic components of a powerdevice switching circuit according to an embodiment of the presentinvention.

FIG. 11 is a view of a first portion of an exemplary control circuit ofan embodiment of the present invention

FIG. 12 is a view of a second portion of an exemplary control circuit ofan embodiment of the present invention.

FIG. 13 is a view of an exemplary circuit connecting LED lamps to anexemplary control circuit of the present invention.

FIGS. 14A, 14B, and 14C are tables showing performance data forbatteries of different chemistries under various conditions utilizedwithin a system of the present invention. Different configurations(e.g., series or parallel) may be utilized by the system of the presentinvention to change the power applied to the batteries, and the powerdrawn from the batteries.

FIG. 15 is a graphical view of exemplary voltage measurements taken withvarious system configurations, which may be used to determine the typeof batteries that are installed in an exemplary system of the presentinvention.

DETAILED DESCRIPTION

Reference will now be made in detail to certain embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. While the invention will be described in reference to theseembodiments, it will be understood that they are not intended to limitthe invention. To the contrary, the invention is intended to coveralternatives, modifications, and equivalents that are included withinthe spirit and scope of the invention. In the following disclosure,specific details are given to provide a thorough understanding of theinvention. However, it will be apparent to one skilled in the art thatthe present invention may be practiced without all of the specificdetails provided.

The present invention concerns novel lighting and charging system thatmay be used in areas that have an unreliable or absent electrical powergrid. The system may include inter alia one or more electric powergeneration devices or “power devices” (e.g., solar panels,thermoelectric generators, etc.), one or more light emitters (e.g., LEDlights), a battery compartment or connectors for receiving and/orconnecting one or more batteries (e.g., AA/14500 size batteries, 12Vbatteries, etc., which may be of various chemistries), one or more portsfor charging external electronic devices (e.g., mobile phones, etc.),and microprocessor firmware and series-parallel switching circuitryconnecting the batteries and/or the power generation devices. Thefirmware and series-parallel switching circuits of the batteries and/orthe power generation devices may allow the system to (1) acceptbatteries of different chemistries and utilize the batteries to run oneor more light emitters connected to the system and/or charge andexternal electronic device connected to the system, (2) automaticallyidentify the battery chemistry of batteries installed in the system andadjust a charge algorithm for the batteries, (3) determine whether thebatteries installed in the system are of mixed chemistry (e.g., multiplebattery types installed in the system simultaneously), (4) automaticallyadjust the configuration of multiple batteries between series andparallel to optimize the battery discharge for powering the LED lights,and, in some cases, powering a USB charge port directly from themultiple batteries, (5) automatically optimize the battery charging, insome cases, while powering a USB charge port based on power output fromone or more power generation devices, (6) switching power sources (e.g.,between power generation devices and batteries) for external electronicdevices plugged into the system and/or the light emitters, based on,e.g., the output of the one or more power generation devices, (7)automatically recognize the dynamically changing power available fromattached power generation devices, (8) automatically adjust theconfiguration of multiple batteries between series and parallelconfigurations to optimize the battery charging based on the dynamicallychanging power available from attached power generation devices (e.g.,solar panels), and (9) automatically adjust the voltage supplied by theone or more power generation devices to the one or more light emittersand/or an external electronic device depending on the current/voltagebalance needed for the light emitters and/or external electronic device,among other beneficial functions.

The presently disclosed system may allow the user to operate the productby installing sets of different types of secondary (rechargeable)batteries based on the purchaser's individual needs and the availabilityof replacement batteries. To prevent damage from incorrect battery typesbeing installed, this invention includes safeguards to protect thedevice from incorrect batteries types, while still allowing operation ofthe lamp even with incorrect types being installed. In addition, thelife expectancy of the chosen batteries are maximized for each batterychemistry by the unit automatically discerning the type of chemistrythat was installed and then using the specific charge algorithm thatoptimizes the life of the battery. For example, using a series ofvoltage measurements taken from a series of configurations of thebatteries, the microprocessor may determine that lithium ion batteriesare attached to the battery connectors (e.g., installed in a batterycompartment) and classify the installed batteries as lithium ion andstore the classification in a memory unit. The microprocessor maycontinue to take voltage readings from the batteries to determine theirstate of discharge, and determine when charging is required. Forexample, a charging operation may be initiated at a pre-determinedthreshold of charge depletion (e.g., a threshold between about 20% and80% depletion, such as about 20% depletion, about 30% depletion, about40% depletion, about 50%, etc.). The amount of voltage and currentsupplied to the batteries during the charging operation will bedetermined by the battery charging logic of the microprocessor, whichtakes into account the state of charge depletion of the batteries, thepower available from the power generation device(s) connected to thesystem, and the charging algorithm of the particular chemical class ofthe installed batteries. When the microprocessor determines that acharging operation is necessary, the microprocessor will apply currentand voltage to the batteries according to a charging algorithm specificto the classification (e.g., the lithium ion chemistry) of the installedbatteries, including bulk, absorption, and float charging phases. As anexample, FIG. 1 provides a graph of a charging profile of a lithium ionbattery, including the bulk, absorption, and float charging phases.Charging profiles for other battery chemistries (e.g., NiMH, NiCd, leadacid, gel, LiFePO4, etc.) are known to those skilled in the art, andthus one of ordinary skill in the art.

The present system also allows for balance charging of a single batteryof a specific battery type according to a charging algorithm of theinstalled battery (e.g., one battery slot of a plurality of batteryslots in the system). Balance charging, or charging one battery at atime to its full potential, allows the battery to be charged to its fullcapacity (whereas when batteries are charged simultaneously the internalresistance of the batteries may vary, resulting differential charging ofthe batteries). The system is operable to recognize that a singlebattery has been installed, switch the battery receivers into parallelconfiguration (e.g., if the battery receivers were configured in series,no complete circuit would be formed and no balance charging would bepossible), and then measure the individual voltage (or current) producedby the battery (e.g., a voltage over about 3.6 V indicates a Li-ionbattery, a voltage between about 3.6 V and about 1.4 V may indicate aLiFePO4 battery, and a voltage of about 1.4 V may indicate a NiMHbattery). Once the battery type is identified, the microprocessor willapply the charging algorithm specific to the particular battery type tothereby charge the battery to its full capacity.

In some embodiments, the presently disclosed system allows the user tochoose which size of solar panel best fits their needs (e.g., based onprice, performance, etc.) and allows for future upgrade of the system toproduce more power by allowing the installation of additional and/orlarger solar panels. The system may automatically recognize the poweravailable from attached solar panels and optimize the batteryconfiguration and/or a battery charging algorithm for optimumperformance based on the dynamically changing output of the solar panel.If the solar panel cannot produce enough current at its maximum powerpoint to power an attached external device and/or light emitter, theunit may adjust its configuration to draw maximum current, and thenautomatically adjust the configuration again when the maximum powerpoint can be maintained.

FIG. 3 provides a view of some of the exemplary elements of a systemaccording an embodiment of the present invention. The exemplary system100 may include a controller 101, a solar panel 102, at least onebattery 103, a table lamp 104, a wall or ceiling lamp 105, and acharging port for an external electronic device 106 a (e.g., a mobilephone). The controller 101 may be in electronic communication with theother elements of the system, and may include a microprocessor havingfirmware logic capable of (1) monitoring the power (voltage and current)produced by the solar panel 102, (2) monitoring the power (voltage andcurrent) available in the battery 103, (3) performing voltage testoperations to determine the type of chemistry of the attached one ormore battery(ies) 103, and (4) controlling and adjusting the current andvoltage supplied to the lamps 104 and 105 and the external mobile device106 a and the one or more batteries 103 during a charging operationaccording to a charging algorithm. The system 100 is a customizablesystem to which various elements may be added (e.g., additional solarpanels) and from which elements can be removed (e.g., one of the lampsmay be removed).

FIG. 4 provides a view of some of the exemplary elements of a secondexample combination of elements. The exemplary system 200 may include abase 201 that houses controller, one or more solar panels 202, a lamp203, and one or more charging port(s) 204 for electronic device(s) 204a. The base 201 may contain a battery receiver (e.g., a compartment) foraccepting batteries of a particular size (e.g., AA/14500 size batteries,etc.), which may accept both primary and secondary batteries of theparticular size. The controller may be in electronic communication withthe other elements of the system (the solar panel 202, the lamp 203, andthe charging port 204), and may include a microprocessor having firmwarelogic capable of (1) monitoring the power (voltage and current) producedby the one or more solar panel(s) 202, (2) monitoring the power (voltageand current) available in the one or more batteries, (3) performingvoltage test operations to determine the type of chemistry of theinstalled batteries, (4) controlling and adjusting the current andvoltage supplied to the lamp 203 and the external mobile device 204 aand the one or more batteries during a charging operation according to acharging algorithm. Once the microprocessor has identified the batterychemistry of the one or more batteries installed in the system, it isoperable to classify the batteries according to their voltage and selecta charge algorithm to apply to the batteries during a charging operationthat accommodates the particular battery chemistry. If batteries ofmixed chemistries or primary batteries are installed in the compartment,the microprocessor may prevent the batteries from being charged and justuse the power available from the batteries until they are drained. Thesystem 200 is a customizable system to which various elements may beadded (e.g., additional solar panels) and from which elements can beremoved (e.g., one of the lamps may be removed).

FIG. 5 provides a diagram overview of the electronic system of alighting/charging system 500 according to an embodiment of the presentinvention. The system 500 includes a controller unit 501 in which amicroprocessor 502 and most of the operative electronics of the systemmay be housed, a solar input 530, one or more USB output for poweringexternal electronic devices (e.g., a mobile phone), and a lamp circuitfor receiving and powering one or more lamps (e.g., LED lamps). Themicroprocessor 502 may be manufactured with firmware logic that receivesinputs (voltage and current signals) from a number of points in theelectronics of the system. The microprocessor 502 may include firmwarelogic that receives signals from a battery circuit 503 providing voltagereadings from one or more batteries installed in battery receivers (BR₁,BR₂ . . . BR_(n)) in the battery circuit 503. The microprocessor maytake multiple voltage readings from the battery receivers with thebatteries in various configurations (e.g., parallel, series, and opencircuit configuration in which current is able to flow through bodydiodes only, etc.). The microprocessor may also be electronicallyconnected to the transistors within the battery circuit that allows themicroprocessor to switch the condition of the transistors (e.g, MOSFETs)within the battery circuit 503 to thereby switch the configuration ofthe one or more batteries in the battery circuit between parallel,series, and other configurations. The microprocessor includes batteryswitching/identification logic firmware 502 b that enables themicroprocessor to switch the configurations of the batteries anddetermine the type of battery installed in the system based on thevoltage readings taken within the battery circuit when the one or morebatteries are in the different configurations. Once the microprocessoridentifies and classifies the type of batteries that are installed inthe battery receivers, the microprocessor stores the batteryidentification in a memory 502 a.

The microprocessor 502 may also include a battery charging logic 502 c.The battery charging logic may interpret voltage readings from theinstalled batteries in view of prior classification of the batteries todetermine when a charging operation to recharge the installed batteriesshould be performed. The battery charging logic 502 c may then apply acharging algorithm to the installed batteries that is selected based onthe classification of the installed batteries stored in the memory 502a. The voltage of the installed batteries and current levels goingthrough the installed batteries are monitored during the chargingoperation, and once the voltage readings from the battery reach atermination threshold set in the battery charging logic 502 c, thebatteries will have reached full charge, and the charging operation isterminated.

During charging operation, the microprocessor may apply current to thebatteries through pulse width modulation (PWM) in order to control theaverage current applied to the batteries during the charging operation.As shown in FIG. 5, PWM is utilized to regulate current being suppliedto the batteries whether charge is being supplied directly from theexternal power device(s) (e.g., solar panels) or through a voltagestep-down (buck) converter 510. The current supplied to the batteriesduring a charging operation is variable depending on (1) theclassification of the installed batteries and (2) the phase (such asbulk, absorption, or float) of the charging operation. Additionally, thedirect source of the current (the power device or buck converter) maychange depending on the charging phase and the amount of currentprovided by the power device(s). For example, during bulk phase chargingwhen relatively high current is required and when the power device cansupply ample current, such as when a solar panel is operating at themaximum power point (MPP), the power may be supplied through the buckconverter 510, but when conditions occur that reduce the amount of powerfrom power device (such as clouds covering the solar panel), the powermay be supplied directly from the power device to harvest the maximumamount of energy.

The microprocessor 502 may be in electronic communication with one ormore transistors (e.g., MOSFETs) in the power switching circuit 531. Thepower switching circuit may include one or more transistors (e.g.,MOSFET, BJT, etc.) and other electronic devices (e.g., Schottky diodes,etc.) to (1) prevent current inrush into the batteries of othersensitive components of the system, (2) provide current and voltagesignals to the microprocessor, and (3) allow the microprocessor tocontrol the routing of current to different points within the controller501 based on (1) the amount of power supplied by the external powerdevice(s), (2) whether the batteries are in a charging operation, and(3) the other power demands of the circuit (e.g., lighting and/or USBdevice charging). The power switching circuit 531 may route power fromthe power device(s) to the buck converter 510 or battery circuit 503 asdirected by the microprocessor 502.

The controller 502 may include a low-dropout regulator 504 that isconnected to both the battery circuit 503 and the power switchingcircuit 531 and provides power to the microprocessor at a predeterminedvalue (e.g., 2.5 V) when power is supplied to the controller 501 byeither the external power device(s) or installed batteries.

The buck converter 510 supplies power to the USB system and the lampcircuit 550 at a stepped-down, pre-determined voltage (e.g., 5V). TheUSB system includes a current limiting power switch that suppliescurrent and voltage to one or more USB plugs in the USB system at thepredetermined USB standard voltage and current. The current to the lampcircuit is regulated by the microprocessor 502 through PWM, as shown inFIG. 5. The lamp circuit 550 must be maintained below a maximum currentto prevent damage to the light emitters (e.g., LEDs) electricallyconnected to the lamp circuit.

The battery circuit of the present invention (e.g., 503 in FIG. 5) mayhave a design that allows the configuration of the batteries to switchedbetween series, parallel, and other configuration in order to allow thesystem (1) to run voltage tests in various configurations to determinethe type of battery(ies) installed in the system, (2) to allow thesystem to perform various charging algorithms on the installed batteries(e.g., balance charging, charging multiple batteries of the same type atonce), (3) to adapt to the power available from the power devices duringa charging operation (e.g., switching to a series configuration whenlower power is provided by solar panels due to light conditions), and(4) to adapt to power demands on the system (e.g., lighting and/or USBcharging demands).

Without limiting the invention, FIG. 6 provides a generalized example ofa battery circuit 600 according to an embodiment of the presentinvention. The battery circuit 600 includes three batteries B₁, B₂, andB₃ that are in electronic communication with six transistors (e.g.,MOSFETs) that are operable to switch the battery configuration betweenseries, parallel, and other configurations at the direction of themicroprocessor μP. It is to be understood that the battery circuit isgeneralized and that it may include various other devices and that theremay be additional devices and circuitry between the transistors and themicroprocessor μP. The transistors may include two normally closedtransistors NC₁ and NC₂ that conduct under default conditions, placingthe batteries in a series configuration, and four normally opentransistors NO₁, NO₂, NO₃, and NO₄ that are open and do not conductunder default conditions. The normally closed transistors may beswitched to an open condition together by the microprocessor μP by afirst set of signals. The normally open transistors may be switched to aclosed condition together by the microprocessor μP by a second setsignals after the normally closed transistors are switch to open by thefirst set of signals. The result of the first and second sets of signalsis that the battery circuit is placed in the parallel configuration,placing the batteries in parallel.

The battery circuit also includes sensors therein in electroniccommunication with the microprocessor μP that enable the microprocessorto measure voltages and/or currents within the battery circuit when thebattery circuit is in various configurations. For example, the batterycircuit 600 includes voltage sensor 601 at the positive end of thebattery circuit and voltage circuit 602 at the negative end of thecircuit, each of which transmit voltage data to the microprocessor μP.The battery circuit 600 may include additional sensors at additionalpositions to measure voltage and/or current. Battery identificationlogic of the microprocessor μP may analyze the data provided by thevoltage sensors 601 and 602 (and/or other sensors in the batterycircuit) when the batteries are in series, parallel, and otherconfigurations in order to determine (1) how many batteries areinstalled in the battery circuit, (2) whether the batteries are of thesame type or mixed chemistry, and/or (3) the particular type ofbattery(ies) that have been installed.

For example, and without limitation, the battery identification logicmay run up to three tests when one or more batteries are installed inthe battery receivers of the battery circuit. Firstly, when a battery isinstalled, its voltage may be measured by one or more voltage sensors inthe battery circuit. If that voltage is then raised by at least acertain amount (e.g., 1.1V), the unit then discerns that a secondbattery has been installed. If that voltage is then raised again by atleast a certain amount (e.g. 1.1V) then the unit knows that a thirdbattery has been installed. Based on the counting of the amount ofbatteries and their total voltage (the default configuration of thecircuit may be in series), the unit determines the type of battery.Available battery types, may be NIMH (1.2V nominal), or non-rechargeableAlkaline (1.5V nominal) or mixed chemistry, or LFP (3.2 V nominal) orLi-Ion (3.7 V nominal). Because three LFP batteries at nominal voltagecan be the same voltage as two fully charged Li-ion batteries incombination with one fully charged NIMH battery, all in series, thebattery identification logic performs additional tests to differentiatebetween different battery chemistries.

If the battery identification logic determines that there are threebatteries, the microprocessor records in memory the total voltage of thethree batteries in series. If the battery identification logicdetermines that the total voltage of the three batteries is higher thana pre-determined threshold (e.g., 4.29V, the maximum limit for threefully charged NIMH batteries in series) then the microprocessor may senda first set of signals that signal the NC₁ and NC₂ transistors to open.Both the normally closed and the normally open transistors of thebattery circuit are open after the first set of signals is sent and theNC₁ and NC₂ transistors are opened, while the normally open transistorshave not been closed. This condition may be referred to herein as“partial parallel” configuration. In the partial parallel configuration,the circuit may be completed through reverse body diodes in the normallyopen transistors (e.g., MOSFETs), which typically cause a drop inmeasured voltage (e.g., a drop of about 0.5 V) of the batteries, and theresulting voltage is analyzed by the battery identification logic andrecorded in the memory of the microprocessor. Subsequently, themicroprocessor may send a second set of signals to the normally opentransistors NO₁, NO₂, NO₃, and NO₄ to their gates and close thetransistors, causing the battery circuit 600 to be in full parallelconfiguration. The battery identification logic analyzes the resultingvoltage of the battery circuit 600 in the parallel configuration and thevoltage data is recorded in the memory of the microprocessor.

Once the voltage data is taken in the series, partial parallel, andparallel battery circuit configurations, the battery identificationlogic of the microprocessor then completes a first test by comparing theseries voltage to the fully parallel voltage. If the voltage in seriesis three times larger (+/−0.3V) than the measured voltage in fullparallel configuration, then all three batteries are of the same typeand they are recorded as lithium based, and the classification isrecorded in the memory of the microprocessor (in this example a 3×comparison is used because there are three batteries, in otherembodiments, the series parallel comparison may use a differentcomparison standard, and the +/−0.3V is used because of the measurementaccuracy of this embodiment, in other embodiments, the acceptablevoltage tolerance may be different). If the calculation results in adifferent of outside of the +/−0.3 V tolerance, the batteries areclassified as mixed chemistry.

Additional tests are subsequently performed because of possibilitiesthat the installed batteries are actually a combination of charged anddepleted LFP and Li-ion batteries that can pass the first test above. Asecond test may be performed using data recorded in the partial parallelconfiguration. The voltage of the three installed batteries tend toequal one another in the partial parallel configuration, but because thevoltage measurements taken in the partial parallel configuration aretaken through the reverse body diodes of the normally open transistors,the average voltage drop of the installed batteries is significantlyless than the pre-determined value (e.g., 0.5 V) expected for chargedbatteries of the same chemistry when batteries of different individualvoltages are installed. If the difference between the measured voltagesof the installed batteries in the partial parallel configuration and thefully parallel configuration is greater than or equal to apre-determined threshold (e.g., about 0.4V), the batteries aredetermined by the battery identification logic to be of the same typeand classed as Li based. If the difference is less than thepre-determined threshold, the batteries are classified as mixedchemistry. The classification of the batteries is recorded in the memoryof the microprocessor (in other embodiments the 0.4V may differ based onthe actual MOSFET transistors that are used).

When the battery identification logic classifies the installed batteriesas mixed chemistry, the battery switching logic configures the batterycircuit 600 in series. Additionally, the microprocessor may configurethe power switching circuit to route the power produced by the batteriesthrough the buck converter, and power may be provided to the lampcircuit through the buck converter to avoid any damage to light emitters(e.g., LED lamps) that may be connected to the lamp circuit.Additionally, the microprocessor may configure the power switchingcircuit to route any power produced by the power devices to thelow-dropout regulator and the buck converter, and disconnect the batterycircuit from any direct connection to the power devices to preventdamage to the installed mixed chemistry batteries.

When the batteries are classified as Li-based, the type of lithiumbattery is determined by the battery identification logic throughanalysis of the total voltage of the installed batteries (Li ionbatteries have higher voltage than LiFePO₄ batteries). However, becausedepleted Li-ion batteries can have the same voltage as charged LiFePO₄batteries, another test may be performed during charging to determinewhether the installed batteries are Li-ion or LiFePO₄ batteries. Li-ionbatteries have a much faster rise in voltage over a given time (dV/dT)when the voltage of the batteries is 3.5 V, in comparison to LiFePO4batteries when their voltage is approximately 3.5. Thus, if thebatteries are classified as LFP, and during charging the dV/dT of thebattery at 3.5V matches that of Li-Ion, then the batteries areautomatically re-classed as Li-Ion, yielding no damage to the batteriesand allowing them to be fully charged.

The voltage of NiMH and primary (e.g., alkaline) batteries are alsosimilar and tests of voltages of the installed batteries in multiplebattery configurations may not reveal whether the installed batteriesare primary, NiMH, or a mixture of both. Thus, the batteryidentification logic also monitors one or more temperature sensor (see,e.g., a thermistor—see the T sensor in FIG. 5) located at or near thebattery receivers. If depleted non-rechargeable primary batteries areinstalled and are classified as NiMH, when a charging operation begins,the primary batteries will immediately heat up to a temperature above apre-determined threshold, thus triggering the temperature sensor(s),which transmit a signal to the battery identification logic. The batteryidentification logic subsequent classifies the batteries asprimary/mixed chemistry, and the microprocessor sends signals to thepower switching circuit to terminate the charging operation.

The battery circuits of the present invention may also be utilized tobalance charge the installed batteries individually. Due to possiblydiffering internal resistance in secondary batteries (Li ion, LiFePO₄,etc.) of the same chemistry installed in the battery receivers, theinstalled secondary batteries may take charge at different rates.Because these batteries can be charged thousands of times, thedifference in charging rates between the batteries may over time lead toone or two of the batteries being significantly undercharged after thecharging operation, thus limiting the total amount of charge that can beheld by the installed batteries. To prevent or correct unbalancedcharging of the installed batteries, a balance charging operation may beperformed by the microprocessor and battery circuit. The balancecharging operation is accomplished by charging one battery at a time. Insome embodiments, and without limitation, the balance charge operationmay be initiated by the user of the system by installing a singlebattery into a first battery receiver. As discussed above, when onebattery is installed into a battery receiver its voltage is measured.When an external power is supplied to the battery circuit during acharging operation, the unit will try to charge the battery. But sincethe other two battery holders do not have batteries in them, no currentwill pass through the battery and therefore no current or voltage willbe sensed by the microprocessor at the negative end of the batterycircuit. In such cases (where a battery voltage is measured at a batteryreceiver, but no current flows to the negative terminal of the batterycircuit), the battery switching logic will change the circuitconfiguration to full parallel to allow current to flow through theinstalled battery and to the negative end of the battery circuit. Thebattery identification logic is then enabled to identify the type ofbattery through voltage and the dV/dT measurements as described above.

In addition to providing novel benefits for charging of installedbatteries, the battery circuit, microprocessor firmware, and additionalelectronic devices of various embodiments of the present invention alsoprovide benefits in managing the discharge of installed batteries andmanagement of power supplies to the lamp circuit and USB chargingsystem. The configuration of the batteries are controlled by the batterydischarge switching logic based on the amount of voltage and currentavailable from the batteries and the power demands on the system (e.g.,powering one or more lamps connected to the lamp circuit, and/or one ormore external electronic devices plugged into the USB charging system).The configuration of the batteries depends on the type of batteriesinstalled in the system. For example, if NiMH batteries are installed,the batteries are maintained in the default series configuration becauseof the relatively low voltage and current provided by the NiMHbatteries. If Li-ion batteries are installed in the system, themicroprocessor may sense the high voltage provided by the batteries inseries and the battery discharge switching logic may direct the batterycircuit to reconfigure the installed batteries in parallel thusmaximizing the amount of time that the batteries can power the lightingelements because of reduced current draw from each battery.Additionally, Li-ion batteries may be switched to series so the powersupplied by the batteries may be supplied to the USB charging circuitthrough the buck converter and to the lamp circuit through the buckconverter in order to regulate the supplied current.

In other embodiments of the invention, and without limitation, both theinstalled power generation units (e.g., solar panels) and the installedbatteries may be controlled by the microprocessor to be switched betweenseries and parallel configurations to adapt to the fluctuations in thepower supplied by the power generation devices (e.g., fluctuations dueto solar conditions) during a charging operation or for powering a lampcircuit or external electronic devices connected to the system, and toadapt the power available from the batteries, e.g., for maximizing theoperation time of the lamp circuit or to support multiple simultaneouspower demands on the system (e.g., charging an external electronicdevice through the USB charging system while providing power to the lampcircuit for running one or more lamps connected to the lamp circuit).

Without limiting the invention, FIG. 7 provides an examplecharging/lighting system 700 overview. The system 700 includes acontroller system 701, a series/parallel switching circuit 702 for thepower generation devices (solar panels), one or more installed powergeneration devices 703 a series/parallel switching circuit 704 for theinstalled batteries, one or more installed batteries 705, one or morelamps 706, and one or more USB ports 707. The controller 701 may includea microprocessor as discussed above having firmware programming thatincludes solar panel switching logic, in addition to batteryidentification logic, battery charging logic, and battery discharging,as discussed herein. The controller system 701 may additionally have asimilar collection of devices therein for routing power to themicroprocessor, the USB charging circuit, and the lamp circuit.

FIG. 8 provides a diagram overview of the electronic system of alighting/charging system 800 according to an embodiment of the presentinvention. The system 800 includes a controller unit 801 in which amicroprocessor 802 and most of the operative electronics of the systemmay be housed, a power generation device receiver 830 in electroniccommunication with the one or more power devices (890, 891, and 892), apower device switching circuit 831, a USB charging system 860 that mayinclude one or more USB inputs for powering external electronic devices(e.g., a mobile phone), a lamp circuit 850 for receiving and poweringone or more lamps (e.g., LED lamps), and a battery switching circuit803. The controller 801 includes a microprocessor 802 that may bemanufactured with firmware logic that receives inputs (voltage andcurrent signals) from a number of points in the electronics of thesystem. The microprocessor 802 may include firmware logic that receivessignals from the battery switching circuit 803 providing voltagereadings from one or more batteries installed in battery receivers(BR₈₁, BR₈₂, and BR₈₃) in the battery switching circuit 803. Themicroprocessor may take multiple voltage readings from the batteryreceivers with the batteries in various configurations (e.g., parallel,series, and open circuit configuration in which current is able to flowthrough body diodes only, etc.) to determine the chemistry of thebatteries installed in the battery receivers, as previously discussedherein. The microprocessor 802 may also include firmware logic thatreceives signals the power generation device switching circuit 831,providing voltage and current readings to determine the amount of poweravailable from the attached power generation devices at a given time.The microprocessor 802 may be electronically connected to thetransistors within the power device switching circuit and the batteryswitching circuit, allowing the microprocessor 802 to switch thecondition of the transistors (e.g, MOSFETs) within the power device andbattery switching circuits to thereby switch the configuration of theinstalled power generation units and the installed batteries betweenparallel and series. The microprocessor 802 may also be in electroniccommunication with series circuit sensor 831 a and parallel circuitsensor 831 b, which provide current and/or voltage data from the powergenerating devices when they are in series and parallel configurations,respectively. The microprocessor includes battery identification logicfirmware 802 b, battery charging logic firmware 802 c, batterydischarging logic firmware 802 d, and solar panel switching logic 802 ethat enables the microprocessor to:

-   -   a. switch the configurations of the batteries between series and        parallel in response to changes in the voltage and current        provided by the power generation devices;    -   b. switch the configuration of the batteries between series and        parallel in response to changes in the power demands of the lamp        circuit and the USB charging circuit;    -   c. determine the type of battery installed in the system based        on the voltage readings taken within the battery circuit when        the one or more batteries are in different configurations;    -   d. determine the voltage and current available from the attached        power generation devices; and    -   e. switch the configuration of the power generation devices        between series and parallel based on the power demands of the        system, including battery charging, the lamp circuit, and the        USB charging circuit and based on instantaneous voltage and        current output of the power generations devices.

Once the microprocessor identifies and classifies the type of batteriesthat are installed in the battery receivers, the microprocessor storesthe battery identification in a memory 802 a. The battery charging logic802 c may interpret voltage readings from the installed batteries inview of the classification of the batteries to determine when a chargingoperation to recharge the installed batteries should be performed. Thebattery charging logic 802 c may then apply a charging algorithm to theinstalled batteries that is selected based on the classification of theinstalled batteries stored in the memory 802 a. The voltage of and thesupplied current to the installed batteries is monitored during thecharging operation, and once the voltage readings from the battery reacha termination threshold set in the battery charging logic 802 c, thebatteries will have reached full charge, and the charging operation isterminated.

During charging operation, the microprocessor may apply current to thebatteries through pulse width modulation (PWM) in order to control theaverage current applied to the batteries during the charging operation(e.g., when the power generating devices are in parallel configuration).As shown in FIG. 8, PWM may be utilized to regulate current beingsupplied to the batteries depending on the series or parallelconfiguration of the external power device(s) (e.g., solar panels) andthe phase of the battery charging operation (e.g. absorption). In someembodiments, and without limitation, a voltage step-down (buck)converter may be utilized to step down voltage supplied by the powergeneration devices, as in the system shown in FIG. 5. In otherembodiments, the system 800 may be designed to receive multiple 12 Vbatteries and 12 V solar panels as the power generation source. In suchembodiments, a buck converter is not necessary to step down voltagebetween the solar panels and batteries. A buck converter 810 may be usedto step down voltage between the batteries and the USB charging circuit860, and in some embodiments the between the batteries and the lampcircuit. In other embodiments (e.g., in embodiments that utilize highervoltage 12V batteries), an additional higher voltage buck converter 870(e.g., 12 V step-down) may be used to step down voltage between thebatteries and the lamp circuit 850 and between the batteries and a lowervoltage buck converter 810 (e.g., 5 V step-down).

The current supplied to the batteries during a charging operation isvariable depending on (1) the classification of the installed batteriesand (2) the phase (bulk, absorption, or float) of the chargingoperation. Additionally, the direct source of the current (the powerdevice or buck converter) may change depending on the charging phase,the amount of current provided by the power device(s). In embodiments inwhich 12 V solar panels and 12V batteries are utilized, the solar panelsand batteries may be matched in their configurations (series orparallel). When power supplied by the solar panels is sufficiently highto charge the batteries (e.g., at or near maximum power point duringbulk phase charging) the solar panels and the batteries may be inparallel configuration. In the case that the solar panels cannot supplysufficient voltage to sustain the voltage and current requirements ofthe charging algorithm applied to the batteries, the microprocessor may(1) direct the power generation device switching circuit 830 to theseries configuration, and (2) direct the battery switching circuit 840to the series configuration. During bulk phase, the power supplied bythe solar panels can be supplied to the batteries without the need formodulation. Once the absorption phase of the charging algorithm begins,the microprocessor applies pulse width modulation to modulate thecurrent (e.g., reduce the current level) according to the chargealgorithm applied by the battery charging logic.

In order to control switching of the switching circuits 831 and 803, themicroprocessor 802 may be in electronic communication with one or moretransistors (e.g., MOSFETs, BJT, etc.) in the switching circuits 831 and803. The power switching circuit 831 may include transistors and otherelectronic devices (e.g., Schottky diodes, etc.) to (1) prevent currentinrush, overvoltage, and other possible damaging conditions fromreaching the batteries of other sensitive components of the system, (2)provide current and voltage signals to the microprocessor, and (3) allowthe microprocessor to control the routing of current to different pointswithin the controller 801 based on (1) the amount of power supplied bythe external power device(s), (2) whether the batteries are in acharging operation, and (3) the other power demands of the circuit(e.g., lighting and/or USB device charging). The power switching circuit831 may route power from the power device(s) to the battery switchingcircuit 803 as directed by the microprocessor 802. In some embodiments(e.g., those that include higher voltage panels and batteries, such 12 Vpanels and 12 V batteries), the power switching circuit 831 and thebattery switching circuit 803 may include over-voltage and reversepolarity protection circuits for both the connection to the powergeneration device switching circuit and the battery switching circuit.These protection circuits are to prevent damage to the sensitivecomponents of the system (e.g., the microprocessor and otherelectronics) that may result from surges in voltage and installationerror resulting in reverse polarity of the batteries or power generationdevices. The components and design of such protection circuits arefamiliar to those skilled in the art.

The controller 801 may include one or more current monitoring devicesfor monitoring current provided by the power devices in both the seriesand parallel configurations. For example, the controller 801 may includea current monitoring device 831 a that connects to the output of thecurrent generation device switching circuit 831 when the powergeneration devices are in series configuration, and a second currentmonitoring device 831 b that connects to the output of the currentgeneration device switching circuit 830 when the power generationdevices are in parallel configuration. The current monitoring devicesmay send signals to the microprocessor regarding the current levelsupplied by the power devices. For example, the current monitoringdevice may send a signal to the microprocessor when the power devicesare in the parallel configuration drop below a threshold required tocharge installed batteries (e.g., during a bulk phase). The power deviceswitching logic firmware may then direct the power device switchingcircuit to switch the power devices to the series configuration.

The controller 801 may include a low-dropout regulator 804 that isconnected to both the battery switching circuit 840 and the powerswitching circuit 831 and provides power to the microprocessor at apredetermined value (e.g., 2.5 V) when power is supplied to thecontroller 801 by either the external power device(s) or installedbatteries. In other embodiments, the power switching circuit may be inelectronic communication with the buck converter, and the buck convertermay provide power to the microprocessor (e.g., 5 V).

The buck converter 810 supplies power to the USB system and the lampcircuit 850 at a stepped-down, pre-determined voltage (e.g., 5V). TheUSB system includes a current limiting power switch that suppliescurrent and voltage to one or more USB plugs in the USB system at thepredetermined USB standard voltage and current. The current to the lampcircuit is regulated by the microprocessor 802 through PWM, as shown inFIG. 5. Power may also be supplied to the lamp circuit 850 from thepower device switching circuit 831 when the power generating devices arein the series configuration. The lamp circuit 850 must be maintainedbelow a maximum current to prevent damage to the light emitters (e.g.,LEDs) electrically connected to the lamp circuit. In some embodiments,and without limitation, the buck converter may also supply power to themicroprocessor. In such in embodiments, the low-dropout regulator may beomitted.

The battery switching circuit 803 may have a design that allows theconfiguration of the batteries to switched between series, parallel, andother configuration in order to allow the system (1) to run voltagetests in various configurations to determine the type of battery(ies)installed in the system, (2) to allow the system to perform variouscharging algorithms on the installed batteries (e.g., balance charging,charging multiple batteries of the same type at once), (3) to adapt tothe power available from the power devices during a charging operation(e.g., switching to a series configuration when lower power is providedby solar panels due to light conditions), and (4) to adapt to powerdemands on the system (e.g., lighting and/or USB charging demands).

FIG. 9 shows an example battery switching circuit 900 that may beutilized in a charging/lighting system like that shown in FIG. 8. Thebattery switching circuit 900 provides a generalized example batterycircuit 900 according to an embodiment of the present invention. Thebattery circuit 900 includes three batteries B₉₁, B₉₂, and B₉₃ that arein electronic communication with six transistors (e.g., MOSFETs) thatare operable to switch the battery configuration between series,parallel, and other configurations at the direction of themicroprocessor μP. It is to be understood that the battery circuit isgeneralized and that it may include various other devices and that theremay be additional devices and circuitry between the transistors and themicroprocessor. The transistors include five normally open transistorsNO₉₁, NO₉₂, NO₉₃, NO₉₄, and NO₉₅ that do not conduct under defaultconditions, and five normally closed transistors NC₉₁, NC₉₂, NC₉₃, NC₉₄,and NC₉₅ that are closed and conduct under default conditions, placingthe batteries in parallel configuration under default conditions. Thenormally closed transistors may be switched to an open condition by themicroprocessor by a first signal provided through output 1 of batterycontroller 901. The normally open transistors may then be switched to aclosed condition by the microprocessor by a second signal providedthrough output 2 of battery controller 901 after the normally closedtransistors are switched to open by the first signal. The result of thefirst and second of signals is that the battery circuit is placed in theseries configuration.

The battery switching circuit may also include sensors therein inelectronic communication with the microprocessor that enable themicroprocessor to measure voltages and/or currents within the batterycircuit when the battery circuit is in various configurations. Forexample, the battery circuit 900 may include voltage sensor 902 at theoutput connection 903 of the battery circuit, which transmits voltagedata to the microprocessor. The battery circuit 900 may includeadditional sensors at additional positions to measure voltage and/orcurrent. Battery identification logic of the microprocessor may analyzethe data provided by the one or more voltage sensors (and/or othersensors in the battery circuit) when the batteries are in series,parallel, and other configurations in order to determine (1) how manybatteries are installed in the battery circuit, (2) whether thebatteries are of the same type or mixed chemistry, and/or (3) theparticular type of battery(ies) that have been installed.

The solar panel switching circuit may be designed similarly to thebattery circuit shown in FIG. 9, with some differences. FIG. 10 shows anexample power device switching circuit 1000 that may be utilized in acharging/lighting system like that shown in FIG. 8. The power deviceswitching circuit 1000 provides a generalized example power device(e.g., solar panel) switching circuit according to an embodiment of thepresent invention. The power device circuit 1000 includes three powerdevice (solar panel) receivers R₁, R₂, and R₃ that are in electroniccommunication with transistors (e.g., MOSFETs) that are operable toswitch the power device configuration between series and parallelconfigurations at the direction of the microprocessor. It is to beunderstood that the power device circuit 1000 is generalized and that itmay include various other devices and that there may be additionaldevices and circuitry between the transistors and the microprocessor.The transistors include six normally open transistors NO₁₁, NO₁₂, NO₁₃,NO₁₄, NO₁₅, and NO₁₆ that do not conduct under default conditions, andfive normally closed transistors NC₁₁, NC₁₂, NC₁₃, NC₁₄, and NC₁₅ thatare closed and conduct under default conditions, placing the powerdevices in parallel configuration under default conditions. The normallyclosed transistors may be switched to an open condition by themicroprocessor by a first signal provided through output 1 of powerdevice controller 1001. The normally open transistors may then beswitched to a closed condition by the microprocessor by a second signalprovided through output 2 of power device controller 1001 after thenormally closed transistors are switched to open by the first signal.The result of the first and second of signals is that the power devicesare placed in the series configuration.

The power device switching circuit may also include sensors therein inelectronic communication with the microprocessor that enable themicroprocessor to measure voltages and/or currents within the powerdevice circuit when the power circuit is in various configurations. Forexample, the power device circuit 1000 may include voltage sensor 1002at the output connection 1003 of the power circuit, which transmitsvoltage data to the microprocessor. The power device circuit 1000 mayinclude additional sensors at additional positions to measure voltageand/or current. The power device switching logic of the microprocessormay be operable to analyze the voltage and current data supplied by thesensors in the power device circuit to switch the configuration of thepower devices between series and parallel. For example, when the voltageand/or current provided by the power devices in parallel configurationdrops below a pre-determined for operating the concurrent power demandon the system, the power device switching logic direct the power deviceswitching circuit to reconfigure the power devices from parallel toseries configuration.

The diagrams provided in FIGS. 3-10 and the accompanying discussionpresent generalized overviews of embodiments of the present invention. Aspecific example of a lighting and charging system according to anembodiment of the present invention is provided below. It is to beunderstood that the specific example is not the only embodiment of theinvention, and that one of ordinary skill in the art would be enabled bythe disclosure provided herein to practice other embodiments of thesystem.

FIGS. 11-12 and the accompanying description provide a detailed exampleof an exemplary system, including the specific components andelectronics thereof. It is to be understood that the electronicsdescribed below may be included in systems of other embodiments (e.g.,as shown in FIGS. 3-10), and provide the functionalities describedabove.

As shown in the schematics in FIGS. 11-12, an exemplary controller mayinclude a microcontroller IC1 may have multiple analog inputs to monitorvoltages throughout the circuit, digital outputs to set specific circuitconfigurations based on the monitored voltages of an attached solarpanel and batteries, outputs capable of pulse width modulation tocontrol battery charging and LED light operation, capacitive touchsensing inputs for control of the LED light output, and firmware thatutilizes machine state firmware theory. The pin functions are asfollows:

-   -   Pin 1—programming the microcontroller    -   Pin 2—measuring the voltage across the temperature sensing        thermistor VR2 through a voltage divider    -   Pin 3—measuring the voltage across R21 to determine the battery        charge current    -   Pin 4—measuring the voltage of Pin 4 on U3 to determine if        current is being drawn by the USB charge port    -   Pin 5—measuring the voltage across the temperature sensing        thermistor VR1 through a voltage divider    -   Pin 6—output to illuminate status LED 3 (green)    -   Pin 7—measuring the voltage across R30 to determine the LED lamp        current    -   Pin 8—ground connection    -   Pin 9—output to illuminate status LED 1 (red)    -   Pin 10—output to illuminate status LED 2 (yellow)    -   Pin 11—output to NPN switching transistor Q5 to close P-Channel        MOSFET Q3    -   Pin 12—PWM output to N-Channel MOSFET Q11 to control the average        current to the LED lamp    -   Pin 13—PWM output to NPN switching transistor Q7 to close and        open P-Channel MOSFET Q8 to control the average current to the        batteries for charging    -   Pin 14—output to NPN switching transistor Q6 to close P-Channel        MOSFETs Q4 and Q10 as a bi-directional switch    -   Pin 15—output to NPN switching transistor Q9 to close P-Channel        MOSFET Q18 to open P-Channel MOSFETs Q14 and Q17 to switch the        battery configuration from series to partial parallel and vice        versa    -   Pin 16—output to close N-Channel MOSFETs Q12 and Q15 and to NPN        switching transistor Q19 to close P-Channel MOSFETS Q13 and Q16        to switch the battery configuration from partial parallel to        fully parallel and vice versa    -   Pin 17—output to turn on the DC-DC non-synchronous step-down        (buck) converter U1    -   Pin 18—output to NPN switching transistor Q2 to close P-Channel        MOSFET Q1    -   Pin 19—ground connection    -   Pin 20—power connection    -   Pin 21—measuring voltage of solar input (via voltage divider to        not overstress port)    -   Pin 22—measuring of voltage of batteries at positive terminal of        battery holder B1 (via voltage divider to not overstress port)    -   Pin 23—capacitive switch 1 sensing (off)    -   Pin 24—capacitive switch 2 sensing (low)    -   Pin 25—capacitive switch 3 sensing (medium)    -   Pin 26—capacitive switch 4 sensing (high)    -   Pin 27—programming the microcontroller    -   Pin 28—programming the microcontroller

The system circuitry may include a stepdown (buck) converter U1 (e.g., aDC-DC non-synchronous step-down converter) and related circuitry thatmay provide a power conversion function, converting relatively highvoltage and relatively low current into 5V with relatively high currentfor stepping down the voltage for use in the one or more charging ports(e.g., USB port) of the system. The step-down converter may provide thepower required for the charging port and the charging of one or moreinstalled batteries (under certain conditions), and for running the oneor more lamps (e.g., LED lamps) for the lighting purposes (under certainconditions), all while isolating the solar panel from the circuit load.The isolation of the solar panel from the load may allow the solar panelto operate near its maximum power point, rather than the solar panelbeing forced to operate at the voltage of the circuitry load as dictatedby Kirchhoff's Voltage Law. For example, with the step-down converter U1in place, the system may allow the attached solar panel capable ofoperating at a MPP of 17V and 0.59 A to maintain the MPP (assuming solarconditions are adequate to support the MPP) and deliver power at 5V witha current capability of approximately 2.0 A to a charging port.

The step-down converter may draw power from either power generationsource such as a solar panel, or from the installed batteries to provideoptimum performance for the consumer. When step-down converter U1 drawspower from the batteries, transistor Q1 (e.g., a MOSFET transistor)remains open so that if a solar panel is plugged into the system, thecurrent will not immediately rush through the batteries or the lamp.Although transistor Q1 may include a reverse body diode that allowspower to conduct from the installed batteries to step-down converter U1,the voltage drop through transistor Q1 creates too much loss; therefore,the voltage from the three batteries may be supplied to the step-downconverter U1 through a low VF Schottkey diode D5. The step-downconverter U1 may be turned on and off by the microcontroller IC1, basedon different operating voltages in the circuit that the microcontrollerIC1 may monitor (e.g., the voltage provided by the one or more solarpanels, and the voltage provided by the one or more installedbatteries).

The system may also include a voltage regulator U2 (e.g., a low-dropoutvoltage regulator) and related circuitry that may provide a controlledpower level (e.g., 2.5V) to the microcontroller IC1. Powering themicrocontroller at 2.5V may allow the microcontroller IC1 to draw powerfrom multiple sources ranging from one or more fully charged or depletedbatteries, and/or sources that provide higher voltages, such as solarpanels. When voltage regulator U2 draws power from the installedbatteries, transistor Q1 remains open such that if one or more solarpanels are plugged into the controller, the current will not immediatelyrush through the installed batteries or the one or more lamps. Thevoltage from the installed batteries may be supplied to the voltageregulator U2 while the transistor Q1 is open through the Schottkey diodeD5. The voltage regulator U2 may also provide a reference voltage (e.g.,set at 2.5V) for the microcontroller IC1 to use in its analogmeasurement of specific voltage levels in the circuit with a higherresolution compared to higher input voltages (e.g., 5V).

The system may include multiple status lights or other indicators andrelated circuitry to provide cues to the user about the status of thesystem. As shown in FIG. 11, the system may include LED 1, LED 2, andLED3, which may each have a different color (e.g., red, yellow, andgreen, respectively) and may provide feedback to the user regardingbattery charge levels (green), status of input power for an externalpower source such as a solar power (yellow), and to let the user know ifa fault has occurred with the external power source or with theinstalled batteries (red).

The system may include a USB dedicated charging port controller andcurrent limiting power switch U3 and related circuitry, which mayprovide auto-detection of USB data line voltages and automaticallyprovide the correct electrical signature on the data lines to chargecompliant devices among multiple dedicated charging schemes. The USBdedicated charging port controller and current limiting power switch U3may also provide a current limiting function so as to charge the USBcompliant device from a power input of an external source such as asolar panel or from the internally installed batteries. Themicrocontroller IC1 may monitor the draw of current by an attachedexternal electronic device through the charging port. The system mayconfigure the batteries (e.g., LFP or Li-Ion batteries) in series toproduce a higher voltage when the system is charging an externalelectronic device (and, optionally, simultaneously powering the LEDlight(s)), and switch the configuration of the batteries to parallelonce the microcontroller IC1 senses that the external electronic deviceis no longer drawing current (the parallel configuration is moreappropriate for powering the LED light(s) alone). In some embodiments,and without limitation, the microcontroller IC1 may control the currentlimiting function of the charging port controller and current limitingpower switch U3 such that a limited amount of current is drawn by anexternal device attached to the USB charging port when power is neededfor other functions; e.g., the operation of the one or more lamps andcharging the installed batteries.

The system may also include a battery compartment or holder for housingand electrically connecting the installed batteries to the system. FIG.12 provides a schematic of an exemplary circuitry associated with thebattery compartment for housing and electrically connected installedbatteries. The compartment may include three independent holders forbatteries B1, B2, and B3, or may be one holder but with each batteryterminal being independent of all other terminals, thus not forcing thebatteries into either serial or parallel configurations.

The controller may include transistors in electronic communication withthe battery compartment and installed batteries that can be used tochange the configuration of the installed batteries (e.g., from seriesto parallel and vice versa) depending on a number of factors. Thosefactors include the power available from attached one or more solarpanels (which varies depending on weather and environmental conditions:clouds, low-light conditions, etc.), the power available from theinstalled batteries, and the current load on the system (e.g., the oneor more lamps and/or an external electronic device). For accuratemeasurement of the battery voltage, the measurement the microcontrollerIC1 may measure the voltage of the batteries when the batteries areneither providing power nor being charged (no load or charge). To do so,the battery measurement may be timed with the pulse width modulation(PWM) timing of the power supply to one or more LED lamps and/or anyexternal electronic devices being powered or charged by the system sothat measurement is made during the time when no current is beingsupplied to LED lamp(s) or the external electronic device(s). Similarly,the battery voltage measurement is always timed with the PWM timing ofthe battery charge so that the measurement is made during the time whenno current is being supplied to the batteries.

The microcontroller IC1 may change the configuration of the installedbatteries to place them in series or in parallel without the batteriesbeing physically moved by changing the state (open or closed) of one ormore transistors (e.g., MOSFETs) located in the control circuitryassociated with the battery compartment. For example, and withoutlimitation, the system includes transistors Q14 and Q17 (e.g., P-ChannelMOSFETs) that may be closed (with transistors Q12, Q 13, Q 15, and Q16being in the open condition) to place the batteries installed in holdersB1, B2, and B3 in a series configuration. The drain of transistor Q14may be connected to the negative terminal of battery holder B1, and thesource of transistor Q14 may be connected to the positive terminal ofbattery holder B2. In addition, the drain of transistor Q17 may beconnected to the negative terminal of battery holder B2 and the sourceof transistor Q17 may be connected to the positive terminal of batteryholder B3. The gates of Q14 and Q17 may be connected to ground throughresistors R34 and R12 such that as the batteries are being installed inbattery holders B1, B2, and B3, the gate to source voltage may bemaximized to cause the two transistors Q14 and Q17 to be closed. Whenthe batteries are installed in holders B1, B2, and B3, transistors Q14and Q17 are in the normally closed switch configuration because of thegate connection to ground and the three batteries are connected inseries with no output from the microcontroller.

Transistors Q13 and Q16 (e.g., P-Channel MOSFETs) in the circuitryassociated with the battery compartment may have their respective drainsconnected to the negative terminals of battery holders B1 and B2, (viatransistors Q14 and Q17 when they are closed) their sources may be bothconnected to the positive terminal of battery holder B1, and their gatesmay be connected to the positive terminal of battery holder B1 (when nocurrent is passing through transistor Q19). In this arrangement, thegate to source voltage of both transistors Q13 and Q16 is near zero andboth transistors Q13 and Q16 are normally open such that with no outputfrom the microcontroller there is no shorting of the negative terminalsof battery holders B1 and B2 to the positive terminal of battery holderB1.

Transistors Q12 and Q15 (e.g., N-Channel MOSFETs) in the circuitryassociated with the battery compartment may have their respective drainsconnected to the positive terminals of battery holders B2 and B3 (viaQ14 and Q17 when they are closed) and may have their sources bothconnected to the negative terminal of battery holder B3. Bothtransistors Q12 and Q15 may have their gates connected to ground via Pin16 of the microcontroller IC1 so the voltage between the gate and sourceof each of the transistors Q12 and Q15 is near zero and both transistorsQ12 and Q15 are normally open so that with no output from themicrocontroller IC1 there may be no shorting of positive terminal ofbattery holder B2 and B3 to the negative terminal of B3.

Each of the transistors associated with the battery compartment (Q12,Q13, Q14, Q15, Q16 and Q17) may include an internal body diode that isoriented in a manner to allow a limited flow of current through thetransistor when the transistor is open. For example, with no externalpower being supplied to the circuitry associated with the batterycompartment, there is a positive voltage at the positive terminal of B1when a battery is installed in the holder B1, and a circuit is completedthrough the source of transistor Q12 via the associated body diode. Insuch a scenario, even though there are no batteries installed in holdersB2 and B3, a circuit is completed and power is supplied to the voltageregulator U2. If the voltage of the installed battery is high enough,the microcontroller IC1 will turn on. The body diode of transistor Q12reduces the voltage provided by the battery (e.g., by about 0.5V), andthe voltage measurement of the battery will consequently beapproximately 0.5V below the actual value. The voltage drop-off may beuseful for checking for mixed chemistry battery combinations, asdiscussed below. Similarly, if a battery is installed in battery holderB2 (without batteries being installed in holders B1 and B3) the sourceof transistor Q13 may be connected to the positive terminal of holder B1and the source of transistor Q15 may be connected negative terminal ofholder B3, such that a circuit is completed through the body diodes oftransistors Q13 and Q15 and power is again supplied to the voltageregulator U2. Also, if the battery voltage is high enough, themicrocontroller IC1 will turn on. Similarly, if a battery is installedin battery holder B3 (without batteries being installed in holders B1and B2), the source of transistor Q16 being connected to the positiveterminal of holder B1, a circuit is completed through the body diode oftransistor Q16 and once again power is supplied to the voltage regulatorU2. As a result, the consumer of this product is not forced to installthe battery in a particular order, making the product moreuser-friendly. Because transistors Q14 and Q17 are to be normally closedwhen batteries are installed as controlled by a voltage differencebetween the gate and source of each device, and because batteries beinginstalled can be as low as 0.7V in their depleted state, the gate tosource threshold voltage of the devices must be sufficiently low toactive the device at 0.7V and still be able to handle the voltagedifference between the source and drain and the requisite currents ofthe product.

For parallel configuration, the order of how the transistors areswitched is important so as not to connect the negative terminals of thebattery holders directly to the positive terminals of the batteryholders, which would cause short circuits. When the batteries are to beplace in parallel configuration, first the transistors Q14 and Q17(e.g., P-Channel MOSFETs) need to be switched open. The microcontrollerIC1 may provide a voltage (and therefore current) from pin 15 (RC4) tothe base of the transistor Q9 (e.g., an NPN switching transistor) whichallows current to pass through the transistor Q9 and thus bring thepotential of its collector to nearly equal the potential of its emitter,which is connected to ground. This may in turn drop the potential of thegate of transistor Q18 (e.g., a P-Channel MOSFET) so that there is largeenough voltage between the gate and source of transistor Q18 to make theswitch close, thus raising the potential of the gates of transistors Q14and Q17. Once the potential of the gates of transistors Q14 and Q17 israised, the voltage between the gates and sources of these two devicesis reduced so that the switches are open and the batteries installed inholders B1, B2, and B3 may be disconnected from one another.

The gate of transistor Q18 may be connected to the collector oftransistor Q9 through a voltage divider so that the gate to sourcevoltage limit of the device is not violated. Because of the specificorientation of transistors Q12, Q13, Q15 and Q16, a circuit may becomplete through the body diodes of the those devices so that thebatteries are still providing power to voltage regulator U2 and thuspower to the microcontroller IC1 so that the system is stilloperational. Because of the fast switching of the transistors Q14 andQ17 (e.g., P-Channel MOSFETs), the voltage change in the circuit can bealmost instantaneous and an RC circuit made up of capacitor C11 andresistors R41 and R34 (and sometimes resistor R12), which describedbelow in further detail, may operate to slow the change in voltagelevels in the circuitry associated with the battery compartment.Consequently, the microcontroller IC1 may pause the switching process(e.g., momentarily make no further changes to the conditions of thetransistors) for several milliseconds (e.g., about 8 ms to about 150 ms,or any value therein) to allow the voltages in the circuit to stabilizebefore initiating further switching in the transistor in the circuitryassociated with the battery compartment.

After the requisite pause, another output from the microcontroller IC1from pin 16 (RC5) may be activated that simultaneously supplies voltageto transistor Q15 and Q12 (e.g., N-Channel MOSFETs) to close them andconnect the negative terminals of battery holders B1 and B2 to thenegative terminal of B3. The output from the microcontroller IC1 mayalso supply a voltage (and therefore current) to the base of transistorQ19 (e.g., NPN switching transistor), which may allow current to passthrough the transistor Q19 to bring the potential of the collectorthereof to nearly equal the potential of the emitter thereof, which isconnected to ground. This in turn may drop the potential of the gate oftransistors Q13 and Q16 (e.g., P-Channel MOSFETs) so that there may be alarge enough voltage between the gate and source of the two transistorsQ13 and Q16 to close them thereby connect the positive terminals ofbattery holders B2 and B3 to the positive terminal of battery holder B1and place the batteries in parallel to one another. The gates oftransistors Q13 and Q16 may be connected to the collector of transistorQ19 through a voltage divider so that the gate to source voltage limitof these devices is not violated. Because the microcontroller IC1 may bepowered at 2.5V (setting its output levels at 2.5V), the transistors Q12and Q15 (e.g., N-Channel MOSFETs) must have a low enough gate to sourcethreshold voltage to allow the devices to fully turn on with a gatepotential of 2.5V, while being able to meet all the other circuitvoltage and current requirements. Batteries that are depleted to avoltage output as low as 0.7V may be installed in the circuit, and thegate to source threshold voltage of the transistors Q13 and Q16 may besufficiently low to activate the device at 0.7V and yet be able tohandle the voltage difference between the source and drain and therequisite currents of the product.

The system may also be capable of switching the installed batteries froma parallel configuration to a series configuration. The above describedprocess for switching the battery configuration from series to parallelmay be performed in opposite order (in reverse) to place the batteriesin series configuration. The microcontroller IC1 may cease the voltageoutput to transistors Q12, Q15 and Q19 to turn them off, and, after therequisite time delay (e.g., about 8 ms to about 180 ms, or any valuetherein), the output from the microcontroller IC1 to transistor Q9 maybe turned off, restoring the circuit to a series configuration.

Several of the transistors in the present system may be MOSFETs, whichhave very fast switch times. Thus, as batteries are being installed, oras the batteries are being switched between series and parallel and backagain, there may be instantaneous changes in voltage due to theswitching or connection of the battery terminals to the battery holderterminals, which may cause an instantaneous surge of current throughtransistors Q14 and/or Q17, depending on which battery holder isreceiving a battery. To compensate for the potential current surges,capacitor C11 and resistors R41 and R34, (and sometimes resistor R12)may be used to create an RC circuit that slows the change in voltagebetween the gate and source of transistors Q14 and Q17 to regulate thecurrent going through the body of the transistors (e.g., MOSFET) andprevent damage to the transistors. When the circuit is in seriesconfiguration, resistor R12 may be connected to ground and included inthe RC circuit. When the batteries are in parallel configuration,transistor Q18 is closed and pin 1 of resistor R12 may be at the samepotential as the positive terminal of battery holder B1. Resistor R12may be sized to limit the amount of leakage current going through it inthis parallel condition of the batteries, and may no longer part of theRC circuit. The transition time from parallel to series may be less thanthe transition time from series to parallel, and the RC circuit isdesigned to assure current is properly limited for theseries-to-parallel transitions and when individual batteries areinstalled.

The system of the present invention may be operable to charge thebatteries installed in holders B1, B2, and B3 in either series orparallel configurations. The microcontroller IC1 may monitor the currentgoing through the batteries. A very low value resistor R21 may belocated between the negative terminal of the battery holder B3 andground (when in series configuration) and between the negative terminalof battery holders B1 and B2 and B3 and ground (when in parallelconfiguration). The microcontroller IC1 may monitor the potential at thepositive side of resistor R21 as current passes through it (after havinggone through the batteries) and then translates that potential into acurrent reading. The microcontroller IC1 calculates both peak currentand average current going through resistor R21. The average amount ofcurrent passing through the batteries is controlled via a pulse widthmodulation (PWM) process by the microcontroller IC1 providing specifictime based pulses of voltage to the base of transistor Q7 (e.g., an NPNswitching transistor), which allows current to pass through thetransistor Q7 and bring the potential of the collector to nearly equalthe potential of the emitter, which is connected to ground. This in turndrops the potential of the gate of transistor Q8 (e.g., a P-ChannelMOSFET) such that there is large enough voltage between the gate andsource of transistor Q8 to activate it and allow it to conduct and allowcurrent to pass through the batteries. The gate of transistor Q8 isconnected to the collector of transistor Q7 through a voltage divider sothat the gate to source voltage limit of the transistor Q8 is notviolated. The source of Q8 is connected to the input power of the solarpanel through transistor Q1 (e.g., a P-Channel MOSFET), or is connectedto the output of the step-down converter U1 through a combination oftransistors Q3, Q4 and Q10 (e.g., MOSFETs).

Because the installed batteries should not be charged when over acertain temperature threshold, one or more thermistor temperaturesensors, such as VR1 and VR2, may be placed at various locations, suchas near the positive terminals of battery holders B1 and B3. If one ormore thermistor temperature sensors (e.g., VR1 and VR2) measure atemperature above a predetermined threshold, battery charging will beinhibited until the unit cools.

The system may provide power for one or more light sources (e.g., one ormore LED lamps). The microcontroller IC1 may actively monitor thecurrent going through the LED lamps. An exemplary LED lamp circuit isshown in FIG. 13. The exemplary lamp circuit includes a connector CON1for electronically connecting to connector CON2 shown in FIG. 11. TheLED lamp circuit may be placed within a housing designed for sitting ona flat surface and/or attachment to a wall or ceiling, for beinganchored in the soil, trees, rock crevices, or other natural anchoringpoints, etc. The connectors CON1 and CON2 may be standard LEDconnectors. A low value resistor R30 (e.g., a resistor having aresistance of about 0.2 ohm) may be located between the negativeterminal of connector CON2, which provides power to the LED lamps LED1and LED2 through connector CON1 as shown in FIG. 13 and ground. Themicrocontroller IC1 may monitor the potential at the positive side ofresistor R30 as current passes through it after having gone through LED1and LED2. The microcontroller IC1 may then translate that potential intoa current reading. The average amount of current passing through theLED1 and LED2 is controlled via a pulse width modulation (PWM) processby the microcontroller IC1. The microcontroller IC1 may provide specifictime based pulses of voltage to the gate of transistor Q11 (e.g., aN-Channel MOSFET), which may raise the potential of the gate of thetransistor Q11 such that there is a large enough voltage between thegate and source of transistor Q11 to allow transistor Q11 to conductcurrent and allow current to pass through LED1 and LED2. The positiveterminal of connector CON2 is connected to the input power of the solarpanel through transistors Q1 and Q3 (e.g., P-Channel MOSFETs), or isconnected to the output of the step-down converter U1 through acombination of transistors Q4 and Q10 (e.g., P-Channel MOSFETs), asdiscussed further below. When the power for the LED 1 and LED 2 isprovided by solar power through the step-down converter U1 and theinstalled batteries are fully charged, transistors Q3 and Q8 may be inthe open state so that power cannot come from the installed batteries,preventing the batteries from being depleted during the lamp operation.

The light output of LED1 and LED2 lamp may be varied by themicrocontroller IC1 using PWM process to control the average currentgoing through LED1 and LED2. The microcontroller IC1 may utilizecapacitive touch sensing pads S1, S2, S3, and S4 to control the currentpassed through LED1 and LED2. The LED lamp typically may be operated ata minimum of 2.8V to achieve full luminosity of the LED1 and LED2.Because LEDs are susceptible to over current due to their inherently lowinternal resistance, the LEDs also have a maximum voltage in which theycan operate (e.g., 4.6V). When the LED lamp is powered through step-downconverter U1, which provides 5V in order to supply the requisite voltagefor the charge port (e.g., a USB port), the voltage needs be reduced soas not to provide too much current to the LED1 and LED2. A low valueresistor R11 may be used to step down the voltage provided by step-downconverter U1 to LED1 and LED2. When power is coming from the installedbatteries in parallel configuration (with transistors Q4 and Q10 in theopen condition and transistors Q8 and Q3 in the closed condition) thevoltage provided by the batteries may not rise above about 4.2V, andthus a step-down resistor may not be necessary. When the installedbatteries are in a series configuration and the total voltage providedby the batteries is less than about 5.25V (e.g., no load is applied andthe installed batteries are of mixed chemistry or Alkaline batteries)step-down converter U1 may remain in an off condition, transistors Q4and Q10 may be in an open condition, and transistors Q8 and Q3 may be ina closed condition, allowing the batteries to provide power to the LEDlamp. Under such system conditions, power from the installed batteriesmay be supplied to LED1 and LED2 without overpowering the LEDs becausethe total voltage supplied by the installed batteries sag under load. Ifwhen the batteries are in series and the total voltage of the batteriesis about 5.25V or more (e.g., no load applied and the installedbatteries are of mixed chemistry), transistor Q3 may in an opencondition, transistor Q8 may be in a closed condition, and power will gofrom the batteries through Schottky diode D5 to power step-downconverter U1. In addition, transistors Q4 and Q10 may be closed so thatenergy from step-down converter U1 can be supplied to the lamp LEDs. Inthis configuration, transistor Q1 remains closed so that if a solarpanel is plugged in, the voltage from the solar panel is not allowed toreach LED1 or LED 2, nor feed through transistors Q4 and Q10 and thusreach the charging port controller and current limiting power switch U3,which may have a maximum voltage input of about 6V.

The arrangement of transistors Q4 and Q10 (e.g., P-Channel MOSFETs) inthe controller circuitry may create a bi-directional circuit switch dueto their sources being connected to one another and having opposing bodydiodes such that when both switches are open, no current may be passedthrough the combination in either direction. The transistors Q4 and Q10may be switched by output from the microcontroller IC1 providing voltage(and therefore current) to the base of the transistor Q6 (e.g., an NPNswitching transistor), which allows current to pass through thetransistor Q6 and thus bring the potential of the collector to nearlyequal the potential of the emitter, which is connected to ground. Thisin turn drops the potential of the gate of the transistors Q4 and Q10(e.g., a P-Channel MOSFETs) such that there is large enough voltage (dueto voltage leakage through the reverse body diodes) between the gate andsource of each of transistors Q4 and Q10 to close the bi-directionalswitch. The gates of transistors Q4 and Q10 are connected to thecollector of transistor Q6 through a voltage divider so that the gate tosource voltage limit of the transistors Q4 and Q10 is not violated.Similarly, transistor Q1 (e.g., a P-Channel MOSFET) is switched byvoltage control from the microcontroller IC1 supplied to the base oftransistor Q2 (e.g., an NPN switching transistor). The gate oftransistor Q1 may be connected to the collector of transistor Q2 througha voltage divider so that the gate to source voltage limit of transistorQ1 is not violated.

The system includes at least one connector configured to electronicallyconnect with a solar panel, such that the solar panel can provide powerto the system. For example, and without limitation, the power generatedby the solar panel may be provided to the circuit though connector CON1shown in FIG. 11 with some overvoltage protection provided byovervoltage protector diode D3 and transient voltage suppressor D2. Thesystem may include a low VF Schottkey barrier diode D1 in electronicconnection with the connector CON1 to provide reverse input voltageprotection and to protect the solar panel from receiving power from thebatteries of the unit at night or in other low-light conditions. Toallow for easy selection of solar panels, this invention may becompatible with standard 12V solar panels, and can withstand the opencircuit voltage supplied by 12V solar panels of 22V. However, it is tobe understood that lower voltage solar panels can also be used. Inaddition, any DC power source having a voltage in the range of about 6Vto about 22V (or any value therein) may be used to power the product.

Operation of the Exemplary Embodiment

Embodiments of the present invention may be operable to both identifyand utilize batteries of different chemistries that are installed intothe battery compartment of the system. In some embodiments, and withoutlimitation, the battery compartment may be configured for a certainstandard sized battery. However, in other embodiments, the batterycompartment may be configured to receive batteries of multiple sizes orthe system may include more than on battery compartment, each of whichmay accept batteries of a different size. The system may acceptbatteries of multiple different chemistries in the required size(s) toallow the user to utilize the types of batteries that are available tohim (which may be limited in remote or underdeveloped areas). Thepresent system may utilize primary batteries, such as zinc-carbon (drycell), zinc-chloride, alkaline, or lithium chemistry; or a secondarybatteries, such as LiFePo₄, NiCd, nickle-metal hydride (NiMH), NiZn, orlithium ion chemistry. Other embodiments may include other availablebattery types such as lead-acid, or yet to be developed chemistries.

Lithium iron phosphate (LiFePo₄, also known as LFP) batteries arecommonly available in the 14500-package size (almost identical to AA)which has nominal voltage of 3.2V, or lithium-ion (Li-Ion) batteries,also in the 14500-package size which have a nominal voltage of 3.7V. LEDlamps typically requires a minimum of 2.8V to achieve full luminosity ofthe LEDs. Either of these kinds of batteries will work well when inparallel configuration, providing the correct voltage to operate the LEDlamp. Both battery types are rechargeable for thousands of cycles givingthem substantial longevity. However, they are too expensive for someconsumers.

Nickle Metal Hydride (NiMH) batteries are another type of secondarybattery that may be used with the present system that is commonlyavailable in AA battery size. This type of battery has a nominal voltageis 1.2V. In order to provide enough voltage to drive the LED lamp, threeNiMH batteries may be configured in series (e.g., three NiMH batteriesin series, four would exceed the maximum operable voltage of LEDs[4.6V]). NiMH batteries are well suited for powering LED lamps based ontheir voltage output, power stored as measured in mAHr, and relativelylow price. The charge storage capacity (and thus charge cycle) iscomparable to LFP and Li-Ion batteries. However, though they are moreprice accessible than the LFP or Li-Ion batteries, they can only takeapproximately 200 recharges before they lose the ability to hold a fullcharge and need to be replaced.

Conventional systems are unable to distinguish between batteries ofdifferent chemistries. Embodiments of the present invention are operableto switch between parallel and serial configurations based on the typeof battery installed in the battery compartment. FIG. 14 is a tableproviding battery data (e.g., voltage output, charging characteristics,etc.) for a few different battery types when installed in the system (itshould be noted that the system is not limited to the three batterytypes shown in FIG. 14, and that FIG. 14 provides only a sample of datathat may utilized in programming the system of the present invention).The microcontroller IC1 may be programmed to alter the configuration ofthe batteries and the load of the system in order to maximize the usefulpower available from the batteries and maximize the life and chargecycle of the batteries based on such performance data for the batterieswithin the system as shown in FIG. 14. When a battery is installed, thecontroller is able to measure its voltage. If that voltage is thenraised above a certain threshold (e.g., 1.1V), the microcontroller IC1may then discern that a second battery has been installed. If thatvoltage is then raised again above a certain threshold then themicrocontroller IC1 may discern that a third battery has been installed.Based on the counting of the amount of batteries and their total voltage(with the default configuration of the circuit in series), the unit maydetermine the type of battery based on the number of batteries and thetotal voltage provided. Because three LFP batteries at nominal voltagecan be the same voltage as two fully charged Li-Ion batteries incombination with one fully charged NiMH battery, all in series, thesystem may be operable to take several additional measurements andperforms several additional tests to more accurately determine thechemistry of the installed batteries.

The microprocessor IC1 may record the total voltage of the threebatteries installed in the compartment while they are in the seriesconfiguration. If this voltage is higher than 4.29V, (the maximum limitfor three fully charged NiMH batteries in series) then the unit turns onthe first output RC4 from the microcontroller IC1 so that transistorsQ14 and Q17 are in the open condition. The circuit is now in partialparallel configuration because transistors Q12, Q13, Q15, and Q16 arealso in the open condition and the circuit is completed through thereverse body diodes of transistors Q12, Q13, Q15, and Q16, whichtypically cause a 0.5V drop in measured voltage of the batteries. Theresulting voltage of the batteries in this configuration may be thenrecorded. Subsequently, the microprocessor IC1 may turn on the secondoutput RC5 from the microcontroller IC1 so that transistors Q12, Q13,Q15, and Q16 are in the closed condition, causing the circuit to be infull parallel configuration and the resulting voltage of the batteriesin this configuration may be recorded.

The microcontroller IC1 may then complete a first test by comparing theseries voltage to the fully parallel voltage. If the voltage in seriesis 3 times larger (plus or minus a tolerance, such as +/−0.3V) than themeasured voltage in full parallel configuration, then all threebatteries are of the same type and they are recorded as lithium based.If the calculation is outside of the +/−0.3V tolerance then thebatteries are classified as mixed chemistry. Because there arecombinations of charged and depleted LFP and Li-Ion batteries that maypass the first test above, a second test may be performed. When takingthe battery measurement in the partial parallel configuration, thevoltage of the three batteries tend to equal one another, but becausethe measurement is through the reverse body diodes of transistors Q12,Q13, Q15 and Q16, the average voltage drop of 0.5V is much less whenbatteries of different individual voltages are installed. Thus, if thedifference between the measured voltage of the batteries in the partialparallel configuration and in the fully parallel configuration isgreater than or equal to about 0.4V, the batteries may be determined tobe of the same type and classed as Li based. If the difference is lessthan about 0.4V, the batteries may be classified as mixed chemistry.

FIG. 15 provides an illustration of an exemplary set of voltagemeasurements taken from installed batteries by the microcontroller IC1.FIG. 15 also points out the points at which the inrush currentprotection provided by transistor Q1 is utilized.

When the batteries are classed as mixed chemistry, the batteryconfiguration may then be placed in series, the step-down converter U1may be turned on, and transistors Q4 and Q10 may be closed, and the unitwill properly operate the LED lamp. However, transistors Q8 and Q3 maybe open and no charging of the batteries will be allowed in order toprevent the damaging of the mixed chemistry batteries. In addition,transistor Q1 remains open such that if a solar panel is plugged in, thecurrent will not immediately rush through the batteries. The system isoperable to provide the voltage from the mixed chemistry batteries inseries through the step-down converter U1 through the low VF Schottkeydiode D5 to power the LED lamp without the risk of damaging thebatteries or the system.

When lithium-based batteries are installed in the battery compartment,the type of lithium battery may be determined by measuring the voltageof the batteries. Initially, the IC1 may classify the batteries as LFPbatteries based on the voltage measurements of the batteries in series,partial parallel, and parallel configurations. However, because depletedLi-Ion batteries can have the same voltage as charged LFP batteries, themicrocontroller IC1 may conduct another test during charging of thebatteries to differentiate the kind of Li-based batteries. Li-Ionbatteries have a much faster rise in voltage in a given time (dV/dT)when the voltage of the batteries is about 3.5V, than do LFP batterieswhen their voltage is approximately 3.5V. Thus, if the batteries areinitially classified as LFP, and during charging the dV/dT of thebattery at 3.5V matches that of Li-Ion, then the microcontroller IC1 mayautomatically re-classify the installed batteries are as Li-Ion withoutdamage to the batteries. The microcontroller IC1 may adjust the chargingalgorithm of the batteries to allow them to be fully charged.

In another example of a secondary test, if depleted non-rechargeablealkaline batteries are installed and are classified as NiMH, whencharging begins, the batteries will immediately heat up, thus triggeringthe thermistor temperature sensors and the charging will be terminated.

The system of the present invention may also be operable to adjust acharging algorithm of the installed batteries to accommodate differencesin charging rates of batteries of the same chemistry. Due to differinginternal resistance in installed batteries of the same type (e.g., LFPbatteries, Li-ion batteries, etc.), the installed batteries may takecharge at different rates. Because secondary batteries can be rechargedup to thousands of times, the difference in charge between batteries ofthe same kind may become significant after repeated recharging. Withoutany adjustment to the charging algorithm, one or more of the installedbatteries may be left undercharged, thus limiting the collective chargelife of the installed batteries and reducing the operation time of thelamp for a single recharge cycle.

To correct this issue, the system of the present invention may balancecharge the installed batteries by charging one battery at a time. Whenone battery is installed its voltage is measured. Depending on thevoltage of the battery, it could be classified as NiMH and the circuitwill stay in the default series configuration. When external power issupplied, the unit will try to charge the battery. However, since theother two battery holders do not have batteries in them, and because ofthe direction of the reverse body diodes in transistors Q12, Q13, Q15,and Q16, no current will pass through the battery and therefore nocurrent will flow through resistor R21. The microcontroller IC1 may thenchange the circuit configuration to full parallel and as current flowsthrough resistor R21, the type of battery will be reclassified to theappropriate type (e.g., LFP or Li-Ion) based on the batteries voltageand the dV/dT measurements taken as described above.

Switching the batteries between series and parallel configurationsyields many benefits that allow the product to be both user-friendly,and to operate in optimum ways under many external factors. The first isadaptability to various battery types and battery longevity whenpowering the LED lamp. For example, due to the different voltagecharacteristics of the various battery types available on the market,the system must be able to adapt the configuration of the batteries inorder to maximize the length of the discharge period of the installedbatteries. For example, since the system can operate with three AA NiMHbatteries, each at 1.2V nominal voltage, the batteries should be inseries to properly power to LED lamp. In this configuration, the lampmay run on high for at least 4 hours when the batteries are fullycharged. However, if Li-Ion batteries are installed and remain in theseries configuration, due to their high total voltage (11.1V nominal)the power may be passed through the step-down converter U1 to convertthe voltage provided by the batteries to 5V. When the lamp LEDs arepowered through the step-down converter U1, the peak current through theLEDs may be about 1.75 Å. Thus, the current provided by the batteries tothe step-down converter U1 may be about 790 mA (1.75 Å*5V/11.1V). Atthis discharge rate, the Li-Ion batteries will only supply power to theLED lamp for about 1 hour. However, when the Li-Ion batteries are in theparallel configuration, not only is the input voltage to the lamp LEDdropped from approximately 5V to approximately 3.7V (on average) buteach of the three batteries supplies one-third of the total current andthe current supplied by each battery may be reduced from about 790 mA toabout 420 mA. The longevity of the batteries is highly dependent on itdischarge rate, and a reduction in the discharge current to about 410 mAmay extend the time the batteries are able to power the LED lamp toabout 2.5 hours, increasing the charge cycle life of the batteries by afactor of about 2.5.

As a further example, if LFP batteries are installed and remain in theseries configuration, due to their high total voltage (9.6V nominal) thepower may pass through the step-down converter U1 to convert the powerto 5V to power the LED lamp. When the lamp LEDs are powered with thestep-down converter U1, the peak current through the LEDs may be about1.75 Å. Thus, the current provided by the batteries to the step-downconverter U1 may be about 910 mA (1.75 Å*5V/9.6V). At this dischargerate, the LFP batteries may only power the LED lamp for 1.5 hours.However, when the LFP batteries are in the parallel configuration, notonly may the input voltage to the lamp LED dropped from approximately 5Vto 3.2V (on average) but each of the three batteries supplies one-thirdof the total current and so the current supplied by each battery may bereduced from about 910 mA to about 240 mA. Due to the dependence of thelongevity of the battery on the discharge rate, when the dischargecurrent is reduced to about 240 mA, the batteries are able to power toLED lamp for 4.0 hours, increasing the charge cycle life of thebatteries by a factor of about 2.7. This invention therefore providesmeasurable advantages to the consumer by allowing the consumer toutilize the batteries that are available to him and/or the batteriesthat best fits his needs, without having to endure short dischargeperiod.

As noted above, when there is solar panel plugged into the unit ofsufficient power, the step-down converter U1 will be turned on and willsupply power to a USB dedicated charging port U3. Three lithium-basedbatteries, when configured in series, may supply enough voltage to powerthe step-down buck converter U1 and therefore the USB dedicated chargingport U3. The system also allows an external electronic device to becharged through the charging port by the batteries alone. Themicrocontroller IC1 normally monitors the battery configuration and loadon the circuit and does not allow an external electronic device to becharged when there is not sufficient power provided by the solar panels.However, the system includes a switching mechanism that allows theconsumer to override the settings made by the microcontroller IC1 andconfigure lithium-based batteries into series. The consumer can switchthe battery configuration to series by momentarily touching the offswitch S1 and the low switch S2 simultaneously. When this is done thecircuit will change to series configuration, with transistors Q1 and Q3in the open condition, transistor Q8 in the closed condition, andstep-down converter U1 turned on. To allow the simultaneous operation ofthe LED lamp (even though it will operate for a shortened duration asdescribed above), transistors Q4 and Q10 may be in the closed condition.In this configuration, an external electronic device can be chargeddirectly from the three lithium-based batteries when solar power is notavailable. When the USB charge port U3 is no longer charging, or whensolar power is available, the microcontroller IC1 will stop the manuallyconfigured operation and again automatically control the circuit.

The present invention is also operable to balance the voltage andcurrent applied to the batteries during charging from the solar panelswhen there is sufficient light for the solar panels to generate powerbased on the type of the installed batteries and the instantaneous powerproduced by the solar panels. As previously discussed, solar panelsproduce certain levels of current at certain voltages based on theirsize (measured in watts) and the amount of incident solar radiation thatthey receive. The relation between voltage and current are defined foreach size of solar panel. At the MPP, solar panels produce a maximumamount of power (combination of voltage and current). The systemoptimizes the charging of batteries by automatically configuring thebatteries in series or parallel and by automatically routing the powerfrom the solar panel through the step-down converter U1 or by routingthe power from the solar panel through Q1 to the batteries, depending onthe particular chemistry of the installed batteries and the poweravailable from the solar panel(s).

In one example, and without limitation, three NiMH batteries may beinstalled in the system, which need to be in series configuration inorder to provide sufficient power to the LED lamp to a sufficient level.Series configuration is also ideal for NiMH battery charging. Thus, NiMHbatteries may be maintained in series configuration whether they arebeing charged or they are powering the LED lamp or charging an externalelectronic device. If the three NiMH batteries were electricallyconnected to the solar panel, the solar panel output voltage may beequal to the battery voltage (under Kirchhoff's Voltage Law). For threeNiMH batteries in series, the nominal voltage would be about 3.6V.However, 3.6V is substantially lower than the voltage of the MPP forstandard 12V solar panels and at that voltage level, not all of thepower that the solar panel can supply can be utilized by the system.

In order to avoid such inefficiencies, the microcontroller IC1 of thepresent system monitors the input voltage of the solar panel and thepeak current and average current going through the batteries duringcharging. Under default conditions, the microcontroller IC1 will opentransistor Q1, turn on step-down converter U1, close transistors Q4,Q10, and Q3, and will use transistor Q8 to provide pulse widthmodulation control of the current through the NIMH batteries. Based onthe no-load voltage of the three batteries in series, themicrocontroller IC1 will charge the batteries in the preferred methodfor NIMH batteries: e.g., a slow charge averaging about 300 mA for aninitial period of about 15 min, then a fast charge with a peak currentof about 750 mA and an average current of about 560 mA until a voltageof about 4.29V is reached indicating the batteries are fully charged,then perform a maintenance charge averaging about 200 mA for a period ofabout 45 minutes. Because this operation may be done through step-downconverter U1, the current being supplied by the solar panel only needsto be about 220 mA (750 mA*5V/17V) and thus a 5 W or larger solar panelcan be used to charge the batteries. The time required for thisoperation may be about 4.5 hours. During this operation, indicator lightLED2 may be on (e.g., continuously) to indicate that there is amplesolar power.

If the available light diminishes (e.g., a cloud moves over the solarpanel), the power output will fall. Also, the consumer may not be ableto afford a 5 W solar panel and may wish to purchase a smaller andtherefore less expensive 3 W solar panel. Under such conditions, thecircuit in its default configuration will not be able to charge thebatteries because the output voltage of the solar panel will drop tonear short-circuit conditions and therefore there will not supply enoughvoltage to turn on the step-down converter U1. If the circuit was leftin this configuration, no charging would occur and valuable energy fromthe sun would be wasted.

Embodiments of the present invention compensate for such conditions. Themicrocontroller IC1 monitors the current and voltage of different pointsin the circuit, and when it senses that there is a solar panel attachedto the product, but that the solar panel cannot produce enough power toturn on step-down converter U1, the microcontroller IC1 will turn offthe step-down converter U1, open transistors Q4, Q10, and Q3 and willclose transistor Q1. Now the solar panel is feeding current directly tothe batteries, at the battery voltage (as explained by Kirchhoff'sVoltage Law) via pulse width modulation through transistor Q8. As aresult, power can be drawn from underpowered or small solar panels tocharge the installed batteries. The charge time will increase due to thelower current going through the batteries, but the circuit automaticallyadjusts for this by concurrently measuring the resulting voltage of thebatteries. During these conditions an indicator light may indicate theparticular charging mode. For example, and without limitation, LED2 mayblink on and off to show that diminished power is available.

The microcontroller IC1 can also switch back to running the powerprovided by the solar panel through the step-down converter whenconditions are appropriate. The microcontroller IC1 repeatedly measuresthe average and peak current, and if the 5 W or larger solar panel thatwas covered by clouds starts to produce sufficiently high levels ofcurrent because the cloud is no longer shading the solar panel, themicrocontroller will automatically open transistor Q1, which will stopcurrent from being drawn from the solar panel and its voltage willinstantaneously recover to open circuit voltage of approximately 22V.The microcontroller IC1 will then sense ample voltage and may turn onstep-down converter U1, close transistors Q4, Q10, and Q3, and operationof the solar panel at the MPP may be restored. To prevent hysteresis,this operation may be cycled no more than once during a designated timeperiod (e.g., a time frame in a range of about 10 to about 100 seconds,such as every 12 seconds or any value or range of values in that range).

When LFP batteries are installed, by default the batteries areconfigured in parallel because it is the optimum configuration foroperating the LED lamp. Like NiMH batteries, the default condition forcharging LFP batteries may be through the step-down converter U1. Themicrocontroller IC1 may classify the batteries as LFP, and it may chargethe batteries in a constant current manner until the no-load voltage ofthe batteries reaches about 3.6V, and it may then charge the LFPbatteries under constant voltage of about 3.6V for a period of about 45min. In a constant current mode, the ideal average current for LFPbatteries is about 265 mA per battery, with a peak current of about 380mA in a pulse width modulation process. Since the batteries are inparallel, the total current going through the batteries is at an averageof about 795 mA and at a peak of about 1140 mA. With these currents,three LFP batteries may be fully charged within about 3 hours. Toprovide this much current while the solar panel is operating at its MPP,the solar panel needs to be of the 10 W size or larger. If the solarpanel is not this large, or if it becomes covered by clouds, themicrocontroller IC1 will automatically recognize the drop deficiency inpower and reconfigure the circuit to compensate for the deficiency.

As the microcontroller IC1 monitors the current and voltage of differentpoints in the circuit, and it senses that there is a solar panelattached to the product, but that the solar panel cannot produce enoughpower to turn on the step-down converter U1, the microcontroller IC1will turn off the step-down converter U1, open transistors Q4, Q10, andQ3, will reconfigure the three LFP batteries into series configuration,and will close transistor Q1. Under these conditions, instead of thecurrent being divided into 3 parts to charge LFP three batteries, all ofthe current will go through the batteries in series, and the batteriesmay be charged in about 3 hours with a 5 W solar panel and in about 3.8hours with a 3 W solar panel. According to Kirchhoff's Voltage Law, thesolar panel when applying current directly through the batteries inseries will be operating at the voltage of the three batteries in seriesand by pulse width modulation through transistor Q8, the batteries willbe properly charged. During this mode of operation, an indicator lightor other indicator device may provide an indicator to notify the user ofthe current functional mode. For example, LED 2 may blink on and off toshow that diminished power is available. Under the above conditions, ifthe batteries had been left in the parallel configuration it may havetaken about 8 hours to fully charge three LFP batteries with a 5 W solarpanel (due the current being divided by the three batteries). Similarly,it would have taken 10 or more hours to fully charge three LFP batterieswith a 3 W solar panel. However, the system of the present invention maybe able to switch the battery configuration between parallel and seriesin order to reduce the charge time for LFP batteries. In order toprotect the LED lamp from overvoltage (due the solar panel operating atnear 10 volts), the operation of the lamp may not be allowed in thisconfiguration.

As the LFP batteries are being charged in the series configuration, whenthe microcontroller IC1 senses that there is sufficient voltage andcurrent, the microcontroller IC1 may automatically open transistor Q1which will stop current from being drawn from the solar panel to resetand its voltage will instantaneously recover to open circuit voltage ofapproximately 22V. The microcontroller IC1 may then sense ample voltageprovided by the solar panel and will turn on step-down converter U1,close transistors Q4, Q10, and Q3, change the battery configuration toparallel, and restore the solar panel to MPP operation. When the circuitis restored to this configuration, the operation of the lamp may beallowed. To prevent hysteresis, this operation may be cycled no morethan once during a designated time period (e.g., a time frame in a rangeof about 10 to about 100 seconds, such as every 12 seconds or any valueor range of values in that range).

In another example in which Li-Ion batteries are installed, by systemdefault the batteries are configured in parallel as this configurationmay be optimal for operating the LED lamp. Like LFP batteries, thesystem default configuration for charging Li-Ion batteries is throughthe step-down converter U1. Since the microcontroller IC1 may identifyand classify the batteries as Li-Ion, it will charge the batteries intheir preferred method of constant current until the no-load voltage ofthe batteries reaches about 4.2V, and then under constant voltage ofabout 4.2V for about 45 min. In the constant current mode, the idealaverage current for Li-Ion batteries is about 230 mA per battery, with apeak current of about 256 mA in a pulse width modulation process. Sincethe batteries are in parallel, the total current going through thebatteries is an average of about 690 mA and a peak of about 770 mA.Applying the above charging protocol, the system will fully charge threeLi-Ion batteries within about 2.25 hours. In order to provide this muchcurrent while the solar panel is operating at its MPP, the solar panelshould be a 5 W panel or larger. If the solar panel is not sufficientlylarge, or if it covered by clouds, the system will automaticallycompensate for the shortfall.

The microcontroller IC1 monitors the current and voltage of differentpoints in the circuit, and when it senses that there is a solar panelattached to the product, but that the solar panel cannot produce enoughpower to turn on step-down converter U1, the microcontroller will turnoff U1, open transistors Q4, Q10, and Q3, will reconfigure the threeLi-Ion batteries into series configuration, and will close transistorQ1. Under these conditions, instead of the current being divided into 3parts to charge three batteries, all of the current will go through thebatteries in series. According to Kirchhoff's Voltage Law, the solarpanel will be operating at the voltage of the three batteries in seriesand by pulse width modulation through transistor Q8, and the batteriesmay be fully charged. If the batteries were left in the parallelconfiguration under the above conditions, it would take around 6.5 hoursto fully charge three LFP batteries with a 3 W solar panel (due thecurrent being divided by the three batteries). But because the system isable to change the battery configuration between parallel and series,the three LFP batteries will charge in about 2.5 hours with a 3 W solarpanel. In order to protect the LED lamp from overvoltage (due the solarpanel operating at near 10 volts), the operation of the lamp may not beallowed in this configuration. Also, during these conditions anindicator light may indicate the particular charging mode. For example,and without limitation, LED2 may blink on and off to show thatdiminished power is available.

As the Li-Ion batteries are being charged in the series configuration,the microcontroller IC1 continues to monitor the voltage and current atvarious points in the system circuitry. If the microcontroller IC1senses that the solar panel is providing sufficient power to charge thebatteries in parallel, it will automatically open transistor Q1, whichwill stop current from being drawn from the solar panel to reset thesolar panel, and its voltage will instantaneously recover to an opencircuit voltage of approximately 22V. The microcontroller IC1 will thensense ample voltage and will turn on step-down converter U1, closetransistors Q4, Q10, and Q3, change the battery configuration toparallel, and the solar panel may be restored MPP operation. To preventhysteresis, this operation may be cycled no more than once during adesignated time period (e.g., a time frame in a range of about 10 toabout 100 seconds, such as every 12 seconds or any value or range ofvalues in that range). When the circuit is restored to the parallelconfiguration, operation of the lamp may once again be allowed.

It should be noted that if the three LFP or Li-Ion batteries were in aseries configuration and a 10 W or larger solar panel was installed, andtransistor Q1 is closed, the peak current through the batteries would betoo high and would damage the batteries. Also, when balance charging LFPand Li-Ion batteries, the battery configuration is always in parallelconfiguration as noted above.

Of special note, when the less popular NiCad secondary batteries areinstalled, because of their similarity to NiMH batteries in theirvoltage and preferred charge methods, they are treated identical to NiMHbatteries.

The present invention concerns self-contained, rechargeable powersystems for areas having unreliable electric power grid systems or noelectric power grid system at all, and methods related thereto. Thepower systems may include one or more solar panels of various sizes toprovide an off-grid power generation source, a compartment for receivingbatteries of various chemistries, a load, and a control circuitry thatis operable to detect the voltage output of the batteries that areinstalled in the system to determine their specific battery chemistryand then adjust the charge algorithm of the batteries to optimize boththe charge capacity and the cycle life of the batteries. The load may beone or more light emitters and/or one or more external electronicdevices connected through the system by a charge port. Unlike inconventional portable or solar power charging and lighting technologies,the control circuitry in the systems of the present invention maymonitors the power provided by the power generation source, the chargeof the batteries, and the required current for running the load, andbased on the various data, the control circuitry may adjust the currentand voltage individually applied to the load and the batteries andadjust the amount of current drawn from the power generation source.

The systems of the present invention may also be highly customizable. Asthe consumer wishes to perform several functions at the same time, suchas charge batteries and charge USB compatible devices and operate thelamp at the simultaneously, this invention allows the consumer toupgrade their solar panel to larger sizes or adding additional solarpanels of the same size to facilitate multiple and various levels ofoperation. In all cases, the invention monitors the available power andoptimizes the performance as described above, prioritizing first withbattery charging, then the addition of external device charging, thenthe addition of lamp operation. Thus, this invention provides optimumperformance for the consumer while allowing the consumer to choose asmaller and therefore lower cost solar panel, or larger and thereforemore powerful solar panels to handle more operations.

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and many modifications andvariations are possible in light of the above teaching. The embodimentswere chosen and described in order to best explain the principles of theinvention and its practical application, to thereby enable othersskilled in the art to best utilize the invention and various embodimentswith various modifications as are suited to the particular usecontemplated.

It is to be understood that variations and modifications of the presentinvention may be made without departing from the scope thereof. It is tobe appreciated that the features disclosed herein may be used differentcombinations and permutations with each other, all falling within thescope of the present invention.

What is claimed is:
 1. A method of operating a charging system,comprising: a. identifying a chemical class of a plurality of batteriesconnected to battery receivers in said system, wherein said systemincludes a plurality of sensors in electronic communication with saidbattery receivers for measuring electrical characteristics of saidplurality of batteries and a microprocessor operable to analyze saidelectrical characteristics of said plurality of batteries to determine(1) whether said plurality of batteries are of a same chemical class and(2) a particular chemical class of said same chemical class; b.monitoring at least one electrical characteristic of at least one powergeneration device in electronic communication with said charging system;c. monitoring voltages of said plurality of batteries; and d. alteringthe configuration of said plurality of batteries between series andparallel configurations based on at least one of said at least oneelectrical characteristic of said at least one power generation device,said voltages of said plurality of batteries, and said particularchemical class of said plurality of batteries during charging of saidbatteries.
 2. The method of claim 1, wherein said battery receivers areelectronically connected by a battery switching circuit operable toalter electronic connections between said battery receivers to configuresaid plurality of batteries in said parallel and series configurations.3. The method of claim 2, wherein said plurality of sensors areelectronically connected to a plurality of points in said batteryswitching circuit.
 4. The method of claim 3, wherein said microprocessoranalyzes said voltages of said plurality of batteries provided at eachof said plurality of points in said battery switching circuit.
 5. Themethod of claim 4, wherein said microprocessor continuously monitorssaid voltages of said plurality of batteries at said plurality of pointsin said battery switching circuit.
 6. The method of claim 4, whereinsaid step of identifying said chemical class of said plurality ofbatteries connected to said battery receivers includes comparing voltageof said plurality of batteries in said parallel configuration with atotal voltage of said batteries in said series configuration.
 7. Themethod of claim 6, wherein said battery switching circuit includes aplurality of transistors having body diodes therein that allow currentto flow through the transistors when the transistors are open.
 8. Themethod of claim 7, wherein said step of identifying said chemical classof said plurality of batteries connected to said battery receiversfurther includes comparing a voltage of said plurality of batteries whenall of said transistors in said battery switching circuit are open tosaid voltage of said plurality of batteries in said parallelconfiguration.
 9. The method of claim 6, wherein said step ofidentifying said chemical class of said plurality of batteries connectedto said battery receivers further includes monitoring voltages of saidplurality of batteries during charging and comparing a rate of change ofsaid voltages of said plurality of batteries to at least one batterycharging profile stored in a memory accessible to said microprocessor,wherein said at least one battery charging profile includes acharacteristic rate of voltage increase during charging for a particularchemical class of batteries.
 10. The method of claim 6, wherein saidstep of identifying said chemical class of said plurality of batteriesconnected to said battery receivers further includes measuring atemperature at or near said battery receivers while voltage is suppliedto said plurality of batteries through said battery receivers, whereinsaid plurality of batteries are classified as primary batteries or mixedchemistry batteries if said temperature rises above a pre-determinedthreshold temperature.
 11. The method of claim 1, wherein said at leastone electrical characteristic of said at least one power generationdevice includes at least one of a voltage and a current.
 12. The methodof claim 1, wherein said at least one power generation device includesat least one solar panel.